int output_synth_data(mpgedit_madbuf_t *ctx)
{
int i;
int rsts;
for(i=0;i<ctx->Synth.pcm.length;i++) {
signed short Sample;
/* Left channel */
Sample=MadFixedToSshort(ctx->Synth.pcm.samples[0][i]);
*(ctx->OutputPtr++) = Sample & 0xff;
*(ctx->OutputPtr++) = Sample >> 8;
/* Right channel. If the decoded stream is monophonic then
* the right output channel is the same as the left one.
*/
if(MAD_NCHANNELS(&ctx->Frame.header)==2) {
Sample=MadFixedToSshort(ctx->Synth.pcm.samples[1][i]);
*(ctx->OutputPtr++) = Sample & 0xff;
*(ctx->OutputPtr++) = Sample >> 8;
}
/* Flush the output buffer if it is full. */
if (ctx->OutputPtr >= ctx->OutputBufferEnd) {
rsts = fwrite(ctx->OutputBuffer, 1, OUTPUT_BUFFER_SIZE, ctx->outfp);
if (rsts != OUTPUT_BUFFER_SIZE) {
fprintf(stderr,"%s: PCM write error (%s).\n",
"main" ,strerror(errno));
return 1;
}
ctx->OutputPtr = ctx->OutputBuffer;
}
}
void
mp3_mad_decode (mp3_info_t *info) {
// copy synthesized samples into readbuffer
int idx = info->mad_synth.pcm.length-info->buffer.decode_remaining;
// stereo
if (MAD_NCHANNELS(&info->mad_frame.header) == 2 && info->info.fmt.channels == 2) {
while (info->buffer.decode_remaining > 0 && info->buffer.readsize > 0) {
*((int16_t*)info->buffer.out) = MadFixedToSshort (info->mad_synth.pcm.samples[0][idx]);
info->buffer.readsize -= 2;
info->buffer.out += 2;
*((int16_t*)info->buffer.out) = MadFixedToSshort (info->mad_synth.pcm.samples[1][idx]);
info->buffer.readsize -= 2;
info->buffer.out += 2;
info->buffer.decode_remaining--;
idx++;
}
}
// mono
else if (MAD_NCHANNELS(&info->mad_frame.header) == 1 && info->info.fmt.channels == 1){
while (info->buffer.decode_remaining > 0 && info->buffer.readsize > 0) {
*((int16_t*)info->buffer.out) = MadFixedToSshort (info->mad_synth.pcm.samples[0][idx]);
info->buffer.readsize -= 2;
info->buffer.out += 2;
info->buffer.decode_remaining--;
idx++;
}
}
// workaround for bad mp3s that have both mono and stereo frames
else if (MAD_NCHANNELS(&info->mad_frame.header) == 1 && info->info.fmt.channels == 2) {
while (info->buffer.decode_remaining > 0 && info->buffer.readsize > 0) {
int16_t sample = MadFixedToSshort (info->mad_synth.pcm.samples[0][idx]);
*((int16_t*)info->buffer.out) = sample;
info->buffer.readsize -= 2;
info->buffer.out += 2;
*((int16_t*)info->buffer.out) = sample;
info->buffer.readsize -= 2;
info->buffer.out += 2;
info->buffer.decode_remaining--;
idx++;
}
}
else if (MAD_NCHANNELS(&info->mad_frame.header) == 2 && info->info.fmt.channels == 1) {
while (info->buffer.decode_remaining > 0 && info->buffer.readsize > 0) {
int16_t sample = MadFixedToSshort (info->mad_synth.pcm.samples[0][idx]);
*((int16_t*)info->buffer.out) = sample;
info->buffer.readsize -= 2;
info->buffer.out += 2;
info->buffer.decode_remaining--;
idx++;
}
}
}
int32 MADDecoder::Decode(uint8* buffer, int32 max_length)
{
int32 bytes_decoded = 0;
if (stereo)
max_length = max_length - 3;
else
max_length = max_length - 1;
while (bytes_decoded < max_length)
{
if (sample < Synth.pcm.length)
{
int16 sample_data;
sample_data = MadFixedToSshort(Synth.pcm.samples[0][sample]);
#ifdef ALEPHONE_LITTLE_ENDIAN
buffer[bytes_decoded++] = sample_data & 0xff;
buffer[bytes_decoded++] = sample_data >> 8;
#else
buffer[bytes_decoded++] = sample_data >> 8;
buffer[bytes_decoded++] = sample_data & 0xff;
#endif
if (stereo)
{
sample_data = MadFixedToSshort(Synth.pcm.samples[1][sample]);
#ifdef ALEPHONE_LITTLE_ENDIAN
buffer[bytes_decoded++] = sample_data & 0xff;
buffer[bytes_decoded++] = sample_data >> 8;
#else
buffer[bytes_decoded++] = sample_data >> 8;
buffer[bytes_decoded++] = sample_data & 0xff;
#endif
}
sample++;
}
else if (!DecodeFrame())
/**
* MP3音乐播放回调函数，
* 负责将解码数据填充声音缓存区
*
* @note 声音缓存区的格式为双声道，16位低字序
*
* @param buf 声音缓冲区指针
* @param reqn 缓冲区帧大小
* @param pdata 用户数据，无用
*/
static int mp3_audiocallback(void *buf, unsigned int reqn, void *pdata)
{
int avail_frame;
int snd_buf_frame_size = (int) reqn;
int ret;
double incr;
signed short *audio_buf = buf;
unsigned i;
uint16_t *output;
UNUSED(pdata);
if (g_status != ST_PLAYING) {
if (handle_seek() == -1) {
__end();
return -1;
}
xAudioClearSndBuf(buf, snd_buf_frame_size);
xrKernelDelayThread(100000);
return 0;
}
while (snd_buf_frame_size > 0) {
avail_frame = g_buff_frame_size - g_buff_frame_start;
if (avail_frame >= snd_buf_frame_size) {
send_to_sndbuf(audio_buf,
&g_buff[g_buff_frame_start * 2],
snd_buf_frame_size, 2);
g_buff_frame_start += snd_buf_frame_size;
audio_buf += snd_buf_frame_size * 2;
snd_buf_frame_size = 0;
} else {
send_to_sndbuf(audio_buf,
&g_buff[g_buff_frame_start * 2], avail_frame, 2);
snd_buf_frame_size -= avail_frame;
audio_buf += avail_frame * 2;
if (stream.buffer == NULL || stream.error == MAD_ERROR_BUFLEN) {
size_t read_size, remaining = 0;
uint8_t *read_start;
int bufsize;
if (stream.next_frame != NULL) {
remaining = stream.bufend - stream.next_frame;
memmove(g_input_buff, stream.next_frame, remaining);
read_start = g_input_buff + remaining;
read_size = BUFF_SIZE - remaining;
} else {
read_size = BUFF_SIZE;
read_start = g_input_buff;
remaining = 0;
}
if (mp3_data.use_buffer)
bufsize =
buffered_reader_read(mp3_data.r, read_start, read_size);
else
bufsize = xrIoRead(mp3_data.fd, read_start, read_size);
if (bufsize <= 0) {
__end();
return -1;
}
if (bufsize < read_size) {
uint8_t *guard = read_start + read_size;
memset(guard, 0, MAD_BUFFER_GUARD);
read_size += MAD_BUFFER_GUARD;
}
mad_stream_buffer(&stream, g_input_buff, read_size + remaining);
stream.error = 0;
}
ret = mad_frame_decode(&frame, &stream);
if (ret == -1) {
if (MAD_RECOVERABLE(stream.error)
|| stream.error == MAD_ERROR_BUFLEN) {
if (stream.error == MAD_ERROR_LOSTSYNC) {
long tagsize = id3_tag_query(stream.this_frame,
stream.bufend -
stream.this_frame);
if (tagsize > 0) {
mad_stream_skip(&stream, tagsize);
}
if (mad_header_decode(&frame.header, &stream) == -1) {
if (stream.error != MAD_ERROR_BUFLEN) {
if (!MAD_RECOVERABLE(stream.error)) {
__end();
return -1;
}
}
} else {
stream.error = MAD_ERROR_NONE;
}
}
g_buff_frame_size = 0;
g_buff_frame_start = 0;
continue;
} else {
__end();
return -1;
}
}
output = &g_buff[0];
if (stream.error != MAD_ERROR_NONE) {
continue;
}
mad_synth_frame(&synth, &frame);
for (i = 0; i < synth.pcm.length; i++) {
signed short sample;
if (MAD_NCHANNELS(&frame.header) == 2) {
/* Left channel */
sample = MadFixedToSshort(synth.pcm.samples[0][i]);
*(output++) = sample;
sample = MadFixedToSshort(synth.pcm.samples[1][i]);
*(output++) = sample;
} else {
sample = MadFixedToSshort(synth.pcm.samples[0][i]);
*(output++) = sample;
*(output++) = sample;
}
}
g_buff_frame_size = synth.pcm.length;
g_buff_frame_start = 0;
incr = frame.header.duration.seconds;
incr +=
mad_timer_fraction(frame.header.duration,
MAD_UNITS_MILLISECONDS) / 1000.0;
g_play_time += incr;
add_bitrate(&g_inst_br, frame.header.bitrate, incr);
}
}
return 0;
}
bool madaudiofile::getNextAudioFrame() {
#ifdef HAVE_MAD_H
#ifdef MADAUDIO_PRINT_DEBUG
printf("Now in getNextAudioFrame()\n");
#endif
u_int8_t *OutputPtr = OutputBuffer;
u_int8_t *GuardPtr = NULL;
while(OutputPtr < OutputBufferEnd) {
/* The input bucket must be filled if it becomes empty or if
* it's the first execution of the loop.
*/
if(Stream->buffer==NULL || Stream->error==MAD_ERROR_BUFLEN ||
frame_count == 0) {
size_t ReadSize,Remaining;
unsigned char *ReadStart;
/* {2} libmad may not consume all bytes of the input
* buffer. If the last frame in the buffer is not wholly
* contained by it, then that frame's start is pointed by
* the next_frame member of the Stream structure. This
* common situation occurs when mad_frame_decode() fails,
* sets the stream error code to MAD_ERROR_BUFLEN, and
* sets the next_frame pointer to a non NULL value. (See
* also the comment marked {4} bellow.)
*
* When this occurs, the remaining unused bytes must be
* put back at the beginning of the buffer and taken in
* account before refilling the buffer. This means that
* the input buffer must be large enough to hold a whole
* frame at the highest observable bit-rate (currently 448
* kb/s). XXX=XXX Is 2016 bytes the size of the largest
* frame? (448000*(1152/32000))/8
*/
if(Stream->next_frame!=NULL) {
Remaining=Stream->bufend-Stream->next_frame;
memmove(InputBuffer,Stream->next_frame,Remaining);
ReadStart=InputBuffer+Remaining;
ReadSize=INPUT_BUFFER_SIZE-Remaining;
}
else
ReadSize=INPUT_BUFFER_SIZE,
ReadStart=InputBuffer,
Remaining=0;
/* Fill-in the buffer. If an error occurs print a message
* and leave the decoding loop. If the end of stream is
* reached we also leave the loop but the return status is
* left untouched.
*/
ReadSize=readData(ReadStart,1,ReadSize,file);
if(ReadSize<=0) {
break; // probably end of file reached and nothing was read
}
/* {3} When decoding the last frame of a file, it must be
* followed by MAD_BUFFER_GUARD zero bytes if one wants to
* decode that last frame. When the end of file is
* detected we append that quantity of bytes at the end of
* the available data. Note that the buffer can't overflow
* as the guard size was allocated but not used the the
* buffer management code. (See also the comment marked
* {1}.)
*
* In a message to the mad-dev mailing list on May 29th,
* 2001, Rob Leslie explains the guard zone as follows:
*
* "The reason for MAD_BUFFER_GUARD has to do with the
* way decoding is performed. In Layer III, Huffman
* decoding may inadvertently read a few bytes beyond
* the end of the buffer in the case of certain invalid
* input. This is not detected until after the fact. To
* prevent this from causing problems, and also to
* ensure the next frame's main_data_begin pointer is
* always accessible, MAD requires MAD_BUFFER_GUARD
* (currently 8) bytes to be present in the buffer past
* the end of the current frame in order to decode the
* frame."
*/
if(reachedEOF) {
GuardPtr=ReadStart+ReadSize;
memset(GuardPtr,0,MAD_BUFFER_GUARD);
ReadSize+=MAD_BUFFER_GUARD;
}
/* Pipe the new buffer content to libmad's stream decoder
* facility.
*/
mad_stream_buffer(Stream,InputBuffer,ReadSize+Remaining);
Stream->error=(mad_error)0;
}
/* Decode the next MPEG frame. The streams is read from the
* buffer, its constituents are break down and stored the the
* Frame structure, ready for examination/alteration or PCM
* synthesis. Decoding options are carried in the Frame
* structure from the Stream structure.
*
* Error handling: mad_frame_decode() returns a non zero value
* when an error occurs. The error condition can be checked in
* the error member of the Stream structure. A mad error is
* recoverable or fatal, the error status is checked with the
* MAD_RECOVERABLE macro.
*
* {4} When a fatal error is encountered all decoding
* activities shall be stopped, except when a MAD_ERROR_BUFLEN
* is signaled. This condition means that the
* mad_frame_decode() function needs more input to complete
* its work. One shall refill the buffer and repeat the
* mad_frame_decode() call. Some bytes may be left unused at
* the end of the buffer if those bytes forms an incomplete
* frame. Before refilling, the remaining bytes must be moved
* to the beginning of the buffer and used for input for the
* next mad_frame_decode() invocation. (See the comments
* marked {2} earlier for more details.)
*
* Recoverable errors are caused by malformed bit-streams, in
* this case one can call again mad_frame_decode() in order to
* skip the faulty part and re-sync to the next frame.
*/
if(mad_frame_decode(Frame,Stream)) {
if(MAD_RECOVERABLE(Stream->error)) {
/* Do not print a message if the error is a loss of
* synchronization and this loss is due to the end of
* stream guard bytes. (See the comments marked {3}
* supra for more informations about guard bytes.)
*/
if(Stream->error!=MAD_ERROR_LOSTSYNC ||
Stream->this_frame!=GuardPtr) {
}
continue;
}
else
if(Stream->error==MAD_ERROR_BUFLEN)
continue; // end of buffer reached --> read more from the file
else {
fprintf(stderr,
"madaudiofile: unrecoverable frame level error (%i).\n",
Stream->error);
break;
}
}
if(frame_count == 0) {
samplerate = Frame->header.samplerate;
#ifdef MADAUDIO_PRINT_DEBUG
printf("Initially setting samplerate to %i\n",samplerate);
#endif
}
#ifdef MADAUDIO_PRINT_DEBUG
if(Frame->header.samplerate != samplerate)
printf("Obs: samplerate changed to %i!\n",Frame->header.samplerate);
#endif
/* Accounting. The computed frame duration is in the frame
* header structure. It is expressed as a fixed point number
* whole data type is mad_timer_t. It is different from the
* samples fixed point format and unlike it, it can't directly
* be added or subtracted. The timer module provides several
* functions to operate on such numbers. Be careful there, as
* some functions of libmad's timer module receive some of
* their mad_timer_t arguments by value!
*/
frame_count++;
mad_timer_add(Timer,Frame->header.duration);
/* Once decoded the frame is synthesized to PCM samples. No errors
* are reported by mad_synth_frame();
*/
mad_synth_frame(Synth,Frame);
/* Synthesized samples must be converted from libmad's fixed
* point number to the consumer format. Here we use unsigned
* 16 bit big endian integers on two channels. Integer samples
* are temporarily stored in a buffer that is flushed when
* full.
*/
int unsigned sr = 0;
for(int i=0;i<Synth->pcm.length;i++) {
signed short Sample;
u_int8_t left[2];
u_int8_t right[2];
/* Left channel */
Sample=MadFixedToSshort(Synth->pcm.samples[0][i]);
left[0]=Sample>>8;
left[1]=Sample&0xff;
/* Right channel. If the decoded stream is monophonic then
* the right output channel is the same as the left one.
*/
if(MAD_NCHANNELS(&Frame->header)==2)
Sample=MadFixedToSshort(Synth->pcm.samples[1][i]);
right[0]=Sample>>8;
right[1]=Sample&0xff;
while(sr < samplerate) {
/* Left channel */
*(OutputPtr++)=left[1];
*(OutputPtr++)=left[0];
/* Right channel. If the decoded stream is monophonic then
* the right output channel is the same as the left one.
*/
*(OutputPtr++)=right[1];
*(OutputPtr++)=right[0];
sr += Synth->pcm.samplerate;
}
sr -= samplerate;
}
if (OutputPtr>=OutputBufferEnd+OUTPUT_BUFFER_SAFETY) {
char cstr[200];
sprintf(cstr,"getNextAudioFrame() writing outside of OutputBuffer:"
" %p >= %p VERY BAD!!!\n", OutputPtr,
OutputBufferEnd+OUTPUT_BUFFER_SAFETY);
throw(string(cstr));
}
} // while(OutputPtr < OutputBufferEnd)
outputLength = OutputPtr-OutputBuffer;
outputPosition = 0;
if (outputLength == 0)
reachedEOF = true;
// If we have breaked out of the loop, but it wasn't because of EOF,
// return false.
if (OutputPtr < OutputBufferEnd && !reachedEOF)
return false;
return true;
#else
cerr << "libmad not available" << endl;
return false;
#endif // HAVE_MAD_H
}
static int
MP3Callback_22k(void *_buf2, unsigned int numSamples, void *pdata)
{
int i;
short *_buf = (short *)_buf2;
unsigned long samplesOut = 0;
numSamples /= 2;
// Playing , so mix up a buffer
if (samplesInOutput > 0)
{
if (samplesInOutput > numSamples) {
write22k_buf((short *) _buf, (short *) OutputBuffer, numSamples * 2);
samplesOut = numSamples;
samplesInOutput -= numSamples;
} else {
write22k_buf((short *) _buf, (short *) OutputBuffer, samplesInOutput * 2);
samplesOut = samplesInOutput;
samplesInOutput = 0;
}
}
while (samplesOut < numSamples)
{
if (Stream.buffer == NULL) {
Stream.error = 0;
mad_stream_buffer(&Stream, mp3_data, size);
}
if (Stream.error == MAD_ERROR_BUFLEN) {
Stream.error = 0;
if (isRepeatMode) {
MP3_Restart();
mad_stream_buffer(&Stream, mp3_data, size);
samplesInOutput = 0;
} else {
MP3_Stop();
return 0;
}
}
if (mad_frame_decode(&Frame, &Stream)) {
if (MAD_RECOVERABLE(Stream.error)) {
return 0;
} else
if (Stream.error == MAD_ERROR_BUFLEN) {
if (! isRepeatMode) {
MP3_Stop();
return 0;
}
} else {
MP3_Stop();
}
}
FrameCount++;
mad_timer_add(&Timer, Frame.header.duration);
mad_synth_frame(&Synth, &Frame);
for (i = 0; i < Synth.pcm.length; i++) {
signed short Sample;
if (samplesOut < numSamples) {
/* Left channel */
Sample = MadFixedToSshort(Synth.pcm.samples[0][i]);
_buf[((samplesOut * 2) * 2) ] = Sample;
_buf[((samplesOut * 2) * 2) + 1] = Sample;
/* Right channel. If the decoded stream is monophonic then
* the right output channel is the same as the left one.
*/
if (MAD_NCHANNELS(&Frame.header) == 2) {
Sample = MadFixedToSshort(Synth.pcm.samples[1][i]);
}
_buf[(((samplesOut * 2) + 1) * 2) ] = Sample;
_buf[(((samplesOut * 2) + 1) * 2) + 1] = Sample;
samplesOut++;
} else {
Sample = MadFixedToSshort(Synth.pcm.samples[0][i]);
OutputBuffer[samplesInOutput * 2] = Sample;
if (MAD_NCHANNELS(&Frame.header) == 2) {
Sample = MadFixedToSshort(Synth.pcm.samples[1][i]);
}
OutputBuffer[samplesInOutput * 2 + 1] = Sample;
samplesInOutput++;
}
}
}
return isPlaying;
}
bool Mp3AudioFileReader::run(AudioProcessor& processor)
{
if (file_ == nullptr) {
return false;
}
enum {
STATUS_OK,
STATUS_INIT_ERROR,
STATUS_READ_ERROR,
STATUS_PROCESS_ERROR
} status = STATUS_OK;
unsigned char input_buffer[INPUT_BUFFER_SIZE + MAD_BUFFER_GUARD];
unsigned char* guard_ptr = nullptr;
unsigned long frame_count = 0;
short output_buffer[OUTPUT_BUFFER_SIZE];
short* output_ptr = output_buffer;
const short* const output_buffer_end = output_buffer + OUTPUT_BUFFER_SIZE;
int channels = 0;
// Decoding options can here be set in the options field of the stream
// structure.
// {1} When decoding from a file we need to know when the end of the file is
// reached at the same time as the last bytes are read (see also the comment
// marked {3} below). Neither the standard C fread() function nor the POSIX
// read() system call provides this feature. We thus need to perform our
// reads through an interface having this feature, this is implemented here
// by the bstdfile.c module.
BStdFile bstd_file(file_);
// Initialize the structures used by libmad.
MadStream stream;
MadFrame frame;
MadSynth synth;
mad_timer_t timer;
mad_timer_reset(&timer);
// This is the decoding loop.
for (;;) {
// The input bucket must be filled if it becomes empty or if it's the
// first execution of the loop.
if (stream.buffer == nullptr || stream.error == MAD_ERROR_BUFLEN) {
size_t read_size;
size_t remaining;
unsigned char* read_start;
// {2} libmad may not consume all bytes of the input buffer. If the
// last frame in the buffer is not wholly contained by it, then that
// frame's start is pointed by the next_frame member of the stream
// structure. This common situation occurs when mad_frame_decode()
// fails, sets the stream error code to MAD_ERROR_BUFLEN, and sets
// the next_frame pointer to a non-NULL value. (See also the comment
// marked {4} below.)
//
// When this occurs, the remaining unused bytes must be put back at
// the beginning of the buffer and taken in account before refilling
// the buffer. This means that the input buffer must be large enough
// to hold a whole frame at the highest observable bit-rate
// (currently 448 kb/s). XXX=XXX Is 2016 bytes the size of the
// largest frame? (448000*(1152/32000))/8
if (stream.next_frame != nullptr) {
remaining = stream.bufend - stream.next_frame;
memmove(input_buffer, stream.next_frame, remaining);
read_start = input_buffer + remaining;
read_size = INPUT_BUFFER_SIZE - remaining;
}
else {
read_size = INPUT_BUFFER_SIZE;
read_start = input_buffer;
remaining = 0;
}
// Fill-in the buffer. If an error occurs print a message and leave
// the decoding loop. If the end of stream is reached we also leave
// the loop but the return status is left untouched.
read_size = bstd_file.read(read_start, 1, read_size);
if (read_size <= 0) {
if (ferror(file_)) {
error_stream << "\nRead error on bit-stream: "
<< strerror(errno) << '\n';
status = STATUS_READ_ERROR;
}
break;
}
// {3} When decoding the last frame of a file, it must be followed
// by MAD_BUFFER_GUARD zero bytes if one wants to decode that last
// frame. When the end of file is detected we append that quantity
// of bytes at the end of the available data. Note that the buffer
// can't overflow as the guard size was allocated but not used the
// the buffer management code. (See also the comment marked {1}.)
//
// In a message to the mad-dev mailing list on May 29th, 2001, Rob
// Leslie explains the guard zone as follows:
//
// "The reason for MAD_BUFFER_GUARD has to do with the way
// decoding is performed. In Layer III, Huffman decoding may
// inadvertently read a few bytes beyond the end of the buffer in
// the case of certain invalid input. This is not detected until
// after the fact. To prevent this from causing problems, and
// also to ensure the next frame's main_data_begin pointer is
// always accessible, MAD requires MAD_BUFFER_GUARD (currently 8)
// bytes to be present in the buffer past the end of the current
// frame in order to decode the frame."
if (bstd_file.eof()) {
guard_ptr = read_start + read_size;
memset(guard_ptr, 0, MAD_BUFFER_GUARD);
read_size += MAD_BUFFER_GUARD;
}
// Pipe the new buffer content to libmad's stream decoder facility.
mad_stream_buffer(&stream, input_buffer, read_size + remaining);
stream.error = MAD_ERROR_NONE;
}
// Decode the next MPEG frame. The streams is read from the buffer, its
// constituents are break down and stored the the frame structure, ready
// for examination/alteration or PCM synthesis. Decoding options are
// carried in the frame structure from the stream structure.
//
// Error handling: mad_frame_decode() returns a non zero value when an
// error occurs. The error condition can be checked in the error member
// of the stream structure. A mad error is recoverable or fatal, the
// error status is checked with the MAD_RECOVERABLE macro.
//
// {4} When a fatal error is encountered all decoding activities shall
// be stopped, except when a MAD_ERROR_BUFLEN is signaled. This
// condition means that the mad_frame_decode() function needs more input
// to complete its work. One shall refill the buffer and repeat the
// mad_frame_decode() call. Some bytes may be left unused at the end of
// the buffer if those bytes forms an incomplete frame. Before
// refilling, the remaining bytes must be moved to the beginning of the
// buffer and used for input for the next mad_frame_decode() invocation.
// (See the comments marked {2} earlier for more details.)
//
// Recoverable errors are caused by malformed bit-streams, in this case
// one can call again mad_frame_decode() in order to skip the faulty
// part and re-sync to the next frame.
if (mad_frame_decode(&frame, &stream)) {
if (MAD_RECOVERABLE(stream.error)) {
// Do not print a message if the error is a loss of
// synchronization and this loss is due to the end of stream
// guard bytes. (See the comment marked {3} above for more
// information about guard bytes.)
if (stream.error != MAD_ERROR_LOSTSYNC ||
stream.this_frame != guard_ptr) {
// For any MP3 file we typically see two errors in the
// first frame processed:
// - lost synchronization
// - reserved header layer value
// This seems to be OK, so don't print these
if (frame_count != 0) {
error_stream << "\nRecoverable frame level error: "
<< mad_stream_errorstr(&stream) << '\n';
}
}
continue;
}
else {
if (stream.error == MAD_ERROR_BUFLEN) {
continue;
}
else {
error_stream << "\nUnrecoverable frame level error: "
<< mad_stream_errorstr(&stream) << '\n';
status = STATUS_READ_ERROR;
break;
}
}
}
// Display the characteristics of the stream's first frame. The first
// frame is representative of the entire stream.
if (frame_count == 0) {
const int sample_rate = frame.header.samplerate;
channels = MAD_NCHANNELS(&frame.header);
dumpInfo(output_stream, frame.header);
if (!processor.init(sample_rate, channels, OUTPUT_BUFFER_SIZE)) {
status = STATUS_PROCESS_ERROR;
break;
}
showProgress(0, file_size_);
}
// Accounting. The computed frame duration is in the frame header
// structure. It is expressed as a fixed point number whole data type is
// mad_timer_t. It is different from the samples fixed point format and
// unlike it, it can't directly be added or subtracted. The timer module
// provides several functions to operate on such numbers. Be careful
// there, as some functions of libmad's timer module receive some of
// their mad_timer_t arguments by value!
frame_count++;
mad_timer_add(&timer, frame.header.duration);
// Once decoded the frame is synthesized to PCM samples. No errors are
// reported by mad_synth_frame();
mad_synth_frame(&synth, &frame);
// Synthesized samples must be converted from libmad's fixed point
// number to the consumer format. Here we use signed 16 bit integers on
// two channels. Integer samples are temporarily stored in a buffer that
// is flushed when full.
for (int i = 0; i < synth.pcm.length; i++) {
// Left channel
short sample = MadFixedToSshort(synth.pcm.samples[0][i]);
*output_ptr++ = sample;
// Right channel. If the decoded stream is monophonic then the right
// output channel is the same as the left one.
if (MAD_NCHANNELS(&frame.header) == 2) {
sample = MadFixedToSshort(synth.pcm.samples[1][i]);
*output_ptr++ = sample;
}
// Flush the output buffer if it is full
if (output_ptr == output_buffer_end) {
long pos = ftell(file_);
showProgress(pos, file_size_);
bool success = processor.process(
output_buffer,
OUTPUT_BUFFER_SIZE / channels
);
if (!success) {
status = STATUS_PROCESS_ERROR;
break;
}
output_ptr = output_buffer;
}
}
}
// If the output buffer is not empty and no error occurred during the last
// write, then flush it.
if (output_ptr != output_buffer && status != STATUS_PROCESS_ERROR) {
int buffer_size = static_cast<int>(output_ptr - output_buffer);
bool success = processor.process(output_buffer, buffer_size / channels);
if (!success) {
status = STATUS_PROCESS_ERROR;
}
}
// Accounting report if no error occurred.
if (status == STATUS_OK) {
// Report 100% done.
showProgress(file_size_, file_size_);
char buffer[80];
// The duration timer is converted to a human readable string with the
// versatile, but still constrained mad_timer_string() function, in a
// fashion not unlike strftime(). The main difference is that the timer
// is broken into several values according some of its arguments. The
// units and fracunits arguments specify the intended conversion to be
// executed.
//
// The conversion unit (MAD_UNIT_MINUTES in our example) also specify
// the order and kind of conversion specifications that can be used in
// the format string.
//
// It is best to examine libmad's timer.c source-code for details of the
// available units, fraction of units, their meanings, the format
// arguments, etc.
mad_timer_string(timer, buffer, "%lu:%02lu.%03u",
MAD_UNITS_MINUTES, MAD_UNITS_MILLISECONDS, 0);
output_stream << "\nFrames decoded: " << frame_count
<< " (" << buffer << ")\n";
}
processor.done();
close();
return status == STATUS_OK;
}
/****************************************************************************
* Main decoding loop. This is where mad is used. *
****************************************************************************/
#define INPUT_BUFFER_SIZE (5*8192)
#define OUTPUT_BUFFER_SIZE 8192 /* Must be an integer multiple of 4. */
static int MpegAudioDecoder(FILE *InputFp, FILE *OutputFp)
{
struct mad_stream Stream;
struct mad_frame Frame;
struct mad_synth Synth;
mad_timer_t Timer;
unsigned char InputBuffer[INPUT_BUFFER_SIZE+MAD_BUFFER_GUARD],
OutputBuffer[OUTPUT_BUFFER_SIZE],
*OutputPtr=OutputBuffer,
*GuardPtr=NULL;
const unsigned char *OutputBufferEnd=OutputBuffer+OUTPUT_BUFFER_SIZE;
int Status=0,
i;
unsigned long FrameCount=0;
bstdfile_t *BstdFile;
/* First the structures used by libmad must be initialized. */
mad_stream_init(&Stream);
mad_frame_init(&Frame);
mad_synth_init(&Synth);
mad_timer_reset(&Timer);
/* Decoding options can here be set in the options field of the
* Stream structure.
*/
/* {1} When decoding from a file we need to know when the end of
* the file is reached at the same time as the last bytes are read
* (see also the comment marked {3} bellow). Neither the standard
* C fread() function nor the POSIX read() system call provides
* this feature. We thus need to perform our reads through an
* interface having this feature, this is implemented here by the
* bstdfile.c module.
*/
BstdFile=NewBstdFile(InputFp);
if(BstdFile==NULL)
{
fprintf(stderr,"%s: can't create a new bstdfile_t (%s).\n",
ProgName,strerror(errno));
return(1);
}
/* This is the decoding loop. */
do
{
/* The input bucket must be filled if it becomes empty or if
* it's the first execution of the loop.
*/
if(Stream.buffer==NULL || Stream.error==MAD_ERROR_BUFLEN)
{
size_t ReadSize,
Remaining;
unsigned char *ReadStart;
/* {2} libmad may not consume all bytes of the input
* buffer. If the last frame in the buffer is not wholly
* contained by it, then that frame's start is pointed by
* the next_frame member of the Stream structure. This
* common situation occurs when mad_frame_decode() fails,
* sets the stream error code to MAD_ERROR_BUFLEN, and
* sets the next_frame pointer to a non NULL value. (See
* also the comment marked {4} bellow.)
*
* When this occurs, the remaining unused bytes must be
* put back at the beginning of the buffer and taken in
* account before refilling the buffer. This means that
* the input buffer must be large enough to hold a whole
* frame at the highest observable bit-rate (currently 448
* kb/s). XXX=XXX Is 2016 bytes the size of the largest
* frame? (448000*(1152/32000))/8
*/
if(Stream.next_frame!=NULL)
{
Remaining=Stream.bufend-Stream.next_frame;
memmove(InputBuffer,Stream.next_frame,Remaining);
ReadStart=InputBuffer+Remaining;
ReadSize=INPUT_BUFFER_SIZE-Remaining;
}
else
ReadSize=INPUT_BUFFER_SIZE,
ReadStart=InputBuffer,
Remaining=0;
/* Fill-in the buffer. If an error occurs print a message
* and leave the decoding loop. If the end of stream is
* reached we also leave the loop but the return status is
* left untouched.
*/
ReadSize=BstdRead(ReadStart,1,ReadSize,BstdFile);
if(ReadSize<=0)
{
if(ferror(InputFp))
{
fprintf(stderr,"%s: read error on bit-stream (%s)\n",
ProgName,strerror(errno));
Status=1;
}
if(feof(InputFp))
fprintf(stderr,"%s: end of input stream\n",ProgName);
break;
}
/* {3} When decoding the last frame of a file, it must be
* followed by MAD_BUFFER_GUARD zero bytes if one wants to
* decode that last frame. When the end of file is
* detected we append that quantity of bytes at the end of
* the available data. Note that the buffer can't overflow
* as the guard size was allocated but not used the the
* buffer management code. (See also the comment marked
* {1}.)
*
* In a message to the mad-dev mailing list on May 29th,
* 2001, Rob Leslie explains the guard zone as follows:
*
* "The reason for MAD_BUFFER_GUARD has to do with the
* way decoding is performed. In Layer III, Huffman
* decoding may inadvertently read a few bytes beyond
* the end of the buffer in the case of certain invalid
* input. This is not detected until after the fact. To
* prevent this from causing problems, and also to
* ensure the next frame's main_data_begin pointer is
* always accessible, MAD requires MAD_BUFFER_GUARD
* (currently 8) bytes to be present in the buffer past
* the end of the current frame in order to decode the
* frame."
*/
if(BstdFileEofP(BstdFile))
{
GuardPtr=ReadStart+ReadSize;
memset(GuardPtr,0,MAD_BUFFER_GUARD);
ReadSize+=MAD_BUFFER_GUARD;
}
/* Pipe the new buffer content to libmad's stream decoder
* facility.
*/
mad_stream_buffer(&Stream,InputBuffer,ReadSize+Remaining);
Stream.error=0;
}
/* Decode the next MPEG frame. The streams is read from the
* buffer, its constituents are break down and stored the the
* Frame structure, ready for examination/alteration or PCM
* synthesis. Decoding options are carried in the Frame
* structure from the Stream structure.
*
* Error handling: mad_frame_decode() returns a non zero value
* when an error occurs. The error condition can be checked in
* the error member of the Stream structure. A mad error is
* recoverable or fatal, the error status is checked with the
* MAD_RECOVERABLE macro.
*
* {4} When a fatal error is encountered all decoding
* activities shall be stopped, except when a MAD_ERROR_BUFLEN
* is signaled. This condition means that the
* mad_frame_decode() function needs more input to complete
* its work. One shall refill the buffer and repeat the
* mad_frame_decode() call. Some bytes may be left unused at
* the end of the buffer if those bytes forms an incomplete
* frame. Before refilling, the remaining bytes must be moved
* to the beginning of the buffer and used for input for the
* next mad_frame_decode() invocation. (See the comments
* marked {2} earlier for more details.)
*
* Recoverable errors are caused by malformed bit-streams, in
* this case one can call again mad_frame_decode() in order to
* skip the faulty part and re-sync to the next frame.
*/
if(mad_frame_decode(&Frame,&Stream))
{
if(MAD_RECOVERABLE(Stream.error))
{
/* Do not print a message if the error is a loss of
* synchronization and this loss is due to the end of
* stream guard bytes. (See the comments marked {3}
* supra for more informations about guard bytes.)
*/
if(Stream.error!=MAD_ERROR_LOSTSYNC ||
Stream.this_frame!=GuardPtr)
{
fprintf(stderr,"%s: recoverable frame level error (%s)\n",
ProgName,MadErrorString(&Stream));
fflush(stderr);
}
continue;
}
else
if(Stream.error==MAD_ERROR_BUFLEN)
continue;
else
{
fprintf(stderr,"%s: unrecoverable frame level error (%s).\n",
ProgName,MadErrorString(&Stream));
Status=1;
break;
}
}
/* The characteristics of the stream's first frame is printed
* on stderr. The first frame is representative of the entire
* stream.
*/
if(FrameCount==0)
if(PrintFrameInfo(stderr,&Frame.header))
{
Status=1;
break;
}
/* Accounting. The computed frame duration is in the frame
* header structure. It is expressed as a fixed point number
* whole data type is mad_timer_t. It is different from the
* samples fixed point format and unlike it, it can't directly
* be added or subtracted. The timer module provides several
* functions to operate on such numbers. Be careful there, as
* some functions of libmad's timer module receive some of
* their mad_timer_t arguments by value!
*/
FrameCount++;
mad_timer_add(&Timer,Frame.header.duration);
/* Between the frame decoding and samples synthesis we can
* perform some operations on the audio data. We do this only
* if some processing was required. Detailed explanations are
* given in the ApplyFilter() function.
*/
if(DoFilter)
ApplyFilter(&Frame);
/* Once decoded the frame is synthesized to PCM samples. No errors
* are reported by mad_synth_frame();
*/
mad_synth_frame(&Synth,&Frame);
/* Synthesized samples must be converted from libmad's fixed
* point number to the consumer format. Here we use unsigned
* 16 bit big endian integers on two channels. Integer samples
* are temporarily stored in a buffer that is flushed when
* full.
*/
for(i=0;i<Synth.pcm.length;i++)
{
signed short Sample;
/* Left channel */
Sample=MadFixedToSshort(Synth.pcm.samples[0][i]);
*(OutputPtr++)=Sample>>8;
*(OutputPtr++)=Sample&0xff;
/* Right channel. If the decoded stream is monophonic then
* the right output channel is the same as the left one.
*/
if(MAD_NCHANNELS(&Frame.header)==2)
Sample=MadFixedToSshort(Synth.pcm.samples[1][i]);
*(OutputPtr++)=Sample>>8;
*(OutputPtr++)=Sample&0xff;
/* Flush the output buffer if it is full. */
if(OutputPtr==OutputBufferEnd)
{
if(fwrite(OutputBuffer,1,OUTPUT_BUFFER_SIZE,OutputFp)!=OUTPUT_BUFFER_SIZE)
{
fprintf(stderr,"%s: PCM write error (%s).\n",
ProgName,strerror(errno));
Status=2;
break;
}
OutputPtr=OutputBuffer;
}
}
}while(1);
/* The input file was completely read; the memory allocated by our
* reading module must be reclaimed.
*/
BstdFileDestroy(BstdFile);
/* Mad is no longer used, the structures that were initialized must
* now be cleared.
*/
mad_synth_finish(&Synth);
mad_frame_finish(&Frame);
mad_stream_finish(&Stream);
/* If the output buffer is not empty and no error occurred during
* the last write, then flush it.
*/
if(OutputPtr!=OutputBuffer && Status!=2)
{
size_t BufferSize=OutputPtr-OutputBuffer;
if(fwrite(OutputBuffer,1,BufferSize,OutputFp)!=BufferSize)
{
fprintf(stderr,"%s: PCM write error (%s).\n",
ProgName,strerror(errno));
Status=2;
}
}
/* Accounting report if no error occurred. */
if(!Status)
{
char Buffer[80];
/* The duration timer is converted to a human readable string
* with the versatile, but still constrained mad_timer_string()
* function, in a fashion not unlike strftime(). The main
* difference is that the timer is broken into several
* values according some of it's arguments. The units and
* fracunits arguments specify the intended conversion to be
* executed.
*
* The conversion unit (MAD_UNIT_MINUTES in our example) also
* specify the order and kind of conversion specifications
* that can be used in the format string.
*
* It is best to examine libmad's timer.c source-code for details
* of the available units, fraction of units, their meanings,
* the format arguments, etc.
*/
mad_timer_string(Timer,Buffer,"%lu:%02lu.%03u",
MAD_UNITS_MINUTES,MAD_UNITS_MILLISECONDS,0);
fprintf(stderr,"%s: %lu frames decoded (%s).\n",
ProgName,FrameCount,Buffer);
}
/* That's the end of the world (in the H. G. Wells way). */
return(Status);
}
