static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret, size;
// AVStream *st = s->streams[0];
uint32_t header = 0;
int64_t oldseek = url_fseek(s->pb, 0, SEEK_CUR);
int res;
MPADecodeContext s_temp;
header = (get_byte(s->pb) << 24 & 0xff000000) + (get_byte(s->pb) << 16 & 0x00ff0000)
+ (get_byte(s->pb) << 8 & 0x0000ff00) + get_byte(s->pb);
res = url_fseek(s->pb, oldseek, SEEK_SET);
if(ff_mpegaudio_decode_header(&s_temp, header) == 1) {
size = MP3_PACKET_SIZE;
} else {
size = s_temp.frame_size;
}
// size= 626;//MP3_PACKET_SIZE;
ret= av_get_packet(s->pb, pkt, size);
pkt->stream_index = 0;
if (ret <= 0) {
return AVERROR(EIO);
}
/* note: we need to modify the packet size here to handle the last
packet */
pkt->size = ret;
return ret;
}
/**
* Try to find Xing/Info/VBRI tags and compute duration from info therein
*/
static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
{
uint32_t v, spf;
unsigned frames = 0; /* Total number of frames in file */
unsigned size = 0; /* Total number of bytes in the stream */
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
MPADecodeHeader c;
int vbrtag_size = 0;
v = avio_rb32(s->pb);
if(ff_mpa_check_header(v) < 0)
return -1;
if (ff_mpegaudio_decode_header(&c, v) == 0)
vbrtag_size = c.frame_size;
if(c.layer != 3)
return -1;
/* Check for Xing / Info tag */
url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
v = avio_rb32(s->pb);
if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
v = avio_rb32(s->pb);
if(v & 0x1)
frames = avio_rb32(s->pb);
if(v & 0x2)
size = avio_rb32(s->pb);
}
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
url_fseek(s->pb, base + 4 + 32, SEEK_SET);
v = avio_rb32(s->pb);
if(v == MKBETAG('V', 'B', 'R', 'I')) {
/* Check tag version */
if(avio_rb16(s->pb) == 1) {
/* skip delay and quality */
url_fseek(s->pb, 4, SEEK_CUR);
frames = avio_rb32(s->pb);
size = avio_rb32(s->pb);
}
}
if(!frames && !size)
return -1;
/* Skip the vbr tag frame */
url_fseek(s->pb, base + vbrtag_size, SEEK_SET);
spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
if(frames)
st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
st->time_base);
if(size && frames)
st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
return 0;
}
/**
* Try to find Xing/Info/VBRI tags and compute duration from info therein
*/
static void mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
{
uint32_t v, spf;
int frames = -1; /* Total number of frames in file */
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
MPADecodeContext c;
AVRational temp;
v = get_be32(s->pb);
if(ff_mpa_check_header(v) < 0)
return;
ff_mpegaudio_decode_header(&c, v);
if(c.layer != 3)
return;
/* Check for Xing / Info tag */
url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
v = get_be32(s->pb);
if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
v = get_be32(s->pb);
if(v & 0x1)
frames = get_be32(s->pb);
}
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
url_fseek(s->pb, base + 4 + 32, SEEK_SET);
v = get_be32(s->pb);
if(v == MKBETAG('V', 'B', 'R', 'I')) {
/* Check tag version */
if(get_be16(s->pb) == 1) {
/* skip delay, quality and total bytes */
url_fseek(s->pb, 8, SEEK_CUR);
frames = get_be32(s->pb);
}
}
if(frames < 0)
return;
spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
temp.num = spf; temp.den = c.sample_rate;
st->duration = av_rescale_q(frames, temp,
st->time_base);
}
/* useful helper to get mpeg audio stream infos. Return -1 if error in
header, otherwise the coded frame size in bytes */
int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
{
MPADecodeHeader s1, *s = &s1;
if (ff_mpa_check_header(head) != 0)
return -1;
if (ff_mpegaudio_decode_header(s, head) != 0)
{
return -1;
}
switch(s->layer)
{
case 1:
avctx->codec_id = CODEC_ID_MP1;
*frame_size = 384;
break;
case 2:
avctx->codec_id = CODEC_ID_MP2;
*frame_size = 1152;
break;
default:
case 3:
avctx->codec_id = CODEC_ID_MP3;
if (s->lsf)
*frame_size = 576;
else
*frame_size = 1152;
break;
}
*sample_rate = s->sample_rate;
*channels = s->nb_channels;
*bit_rate = s->bit_rate;
avctx->sub_id = s->layer;
return s->frame_size;
}
