sboolean MP3Stream_SeekTo( channel_t *ch, float fTimeToSeekTo )
{
const float fEpsilon = 0.05f; // accurate to 1/50 of a second, but plus or minus this gives 1/10 of second
MP3Stream_Rewind( ch );
//
// sanity... :-)
//
const float fTrackLengthInSeconds = MP3Stream_GetPlayingTimeInSeconds( &ch->MP3StreamHeader );
if (fTimeToSeekTo > fTrackLengthInSeconds)
{
fTimeToSeekTo = fTrackLengthInSeconds;
}
// now do the seek...
//
while (1)
{
float fPlayingTimeElapsed = MP3Stream_GetPlayingTimeInSeconds( &ch->MP3StreamHeader ) - MP3Stream_GetRemainingTimeInSeconds( &ch->MP3StreamHeader );
float fAbsTimeDiff = fabs(fTimeToSeekTo - fPlayingTimeElapsed);
if ( fAbsTimeDiff <= fEpsilon)
return qtrue;
// when decoding, use fast-forward until within 3 seconds, then slow-decode (which should init stuff properly?)...
//
int iBytesDecodedThisPacket = C_MP3Stream_Decode( &ch->MP3StreamHeader, (fAbsTimeDiff > 3.0f) ); // bFastForwarding
if (iBytesDecodedThisPacket == 0)
break; // EOS
}
return qfalse;
}
// decode one packet of MP3 data only (typical output size is 2304, or 2304*2 for stereo, so input size is less
//
// return is decoded byte count, else 0 for finished
//
int MP3Stream_Decode( LP_MP3STREAM lpMP3Stream, qboolean bDoingMusic )
{
lpMP3Stream->iCopyOffset = 0;
if (0)//!bDoingMusic)
{
// SOF2: need to make a local buffer up so we can decode the piece we want from a contiguous bitstream rather than
// this linklist junk...
//
// since MP3 packets are generally 416 or 417 bytes in length it seems reasonable to just find which linked-chunk
// the current read offset lies within then grab the next one as well (since they're 2048 bytes) and make one
// buffer with just the two concat'd together. Shouldn't be much of a processor hit.
//
sndBuffer *pChunk = (sndBuffer *) lpMP3Stream->pbSourceData;
//
// may as well make this static to avoid cut down on stack-validation run-time...
//
static byte byRawBuffer[SND_CHUNK_SIZE_BYTE*2]; // *2 for byte->short // easily enough to decode one frame of MP3 data, most are 416 or 417 bytes
// fast-forward to the correct chunk...
//
int iBytesToSkipPast = lpMP3Stream->iSourceReadIndex;
while (iBytesToSkipPast >= SND_CHUNK_SIZE_BYTE)
{
pChunk = pChunk->next;
if (!pChunk)
{
// err.... reading off the end of the data stream guys...
//
// pChunk = (sndBuffer *) lpMP3Stream->pbSourceData; // restart
return 0; // ... 0 bytes decoded, so will just stop caller-decoder all nice and legal as EOS
}
iBytesToSkipPast -= SND_CHUNK_SIZE_BYTE;
}
// ok, pChunk is now the 2k or so chunk we're in the middle of...
//
int iChunk1BytesToCopy = SND_CHUNK_SIZE_BYTE - iBytesToSkipPast;
memcpy(byRawBuffer,((byte *)pChunk->sndChunk) + iBytesToSkipPast, iChunk1BytesToCopy);
//
// concat next chunk on to this as well...
//
pChunk = pChunk->next;
if (pChunk)
{
memcpy(byRawBuffer + iChunk1BytesToCopy, pChunk->sndChunk, SND_CHUNK_SIZE_BYTE);
}
else
{
memset(byRawBuffer + iChunk1BytesToCopy, 0, SND_CHUNK_SIZE_BYTE);
}
// now we need to backup some struct fields, fake 'em, do the lo-level call, then restore 'em...
//
byte *pbSourceData_Old = lpMP3Stream->pbSourceData;
int iSourceReadIndex_Old= lpMP3Stream->iSourceReadIndex;
lpMP3Stream->pbSourceData = &byRawBuffer[0];
lpMP3Stream->iSourceReadIndex= 0; // since this is zero, not the buffer offset within a chunk, we can play tricks further down when restoring
unsigned int uiBytesDecoded = C_MP3Stream_Decode( lpMP3Stream );
lpMP3Stream->iSourceReadIndex += iSourceReadIndex_Old; // note '+=' rather than '=', to take account of movement.
lpMP3Stream->pbSourceData = pbSourceData_Old;
return uiBytesDecoded;
}
else
{
// SOF2 music, or EF1 anything...
//
return C_MP3Stream_Decode( lpMP3Stream );
}
}
