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transcode: improve mpeg2 global (meta) data parser

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This commit is contained in:
Jaroslav Kysela 2014-11-27 08:55:16 +01:00
parent 60574bf3e4
commit c2c5b81330
2 changed files with 33 additions and 30 deletions
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4
src/parsers/parser_avc.c
View file

@ -106,13 +106,13 @@ avc_parse_nal_units_buf(const uint8_t *buf_in, uint8_t **buf, int *size)
}
static uint32_t
static inline uint32_t
RB32(const uint8_t *d)
{
return (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
}
static uint32_t
static inline uint32_t
RB24(const uint8_t *d)
{
return (d[0] << 16) | (d[1] << 8) | d[2];

59
src/plumbing/transcoding.c
View file

@ -775,8 +775,15 @@ transcoder_stream_audio(transcoder_t *t, transcoder_stream_t *ts, th_pkt_t *pkt)
}
/**
*
* Parse MPEG2 header, simplifier version (we know what ffmpeg/libav generates
*/
static inline uint32_t
RB32(const uint8_t *d)
{
return (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
}
static void
extract_mpeg2_global_data(th_pkt_t *n, uint8_t *data, int len)
{
@ -799,43 +806,39 @@ non intra quantizer matrix 0 or 64*8
Minimal of 12 bytes.
*/
uint32_t *mpeg2_header = (uint32_t *)data;
if (*mpeg2_header == 0xb3010000) { // SEQ_START_CODE
// Need to determine lentgh of header.
int hs = 12;
int header_size = 12;
if (len >= hs && RB32(data) == 0x000001b3) { // SEQ_START_CODE
// load intra quantizer matrix
uint8_t matrix_enabled = (((uint8_t)*(data+(header_size-1)) & 0x02) == 0x02);
if (matrix_enabled)
header_size += 64;
if (data[hs-1] & 0x02) {
if (hs + 64 < len) return;
hs += 64;
}
//load non intra quantizer matrix
matrix_enabled = (((uint8_t)*(data+(header_size-1)) & 0x01) == 0x01);
if (matrix_enabled)
header_size += 64;
// load non intra quantizer matrix
if (data[hs-1] & 0x01) {
if (hs + 64 < len) return;
hs += 64;
}
// See if we have the first EXT_START_CODE. Normally 10 bytes
// https://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpeg12enc.c;h=3376f1075f4b7582a8e4556e98deddab3e049dab;hb=HEAD#l272
mpeg2_header = (uint32_t *)(data+(header_size));
if (*mpeg2_header == 0xb5010000) { // EXT_START_CODE
header_size += 10;
if (hs + 10 <= len && RB32(data + hs) == 0x000001b5) // EXT_START_CODE
hs += 10;
// See if we have the second EXT_START_CODE. Normally 12 bytes
// https://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpeg12enc.c;h=3376f1075f4b7582a8e4556e98deddab3e049dab;hb=HEAD#l291
mpeg2_header = (uint32_t *)(data+(header_size));
if (*mpeg2_header == 0xb5010000) { // EXT_START_CODE
header_size += 12;
// See if we have the second EXT_START_CODE. Normally 12 bytes
// https://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpeg12enc.c;h=3376f1075f4b7582a8e4556e98deddab3e049dab;hb=HEAD#l291
// ffmpeg libs might have this block missing
if (hs + 12 <= len && RB32(data + hs) == 0x000001b5) // EXT_START_CODE
hs += 12;
// See if we have the second GOP_START_CODE. Normally 31 bits == 4 bytes
// https://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpeg12enc.c;h=3376f1075f4b7582a8e4556e98deddab3e049dab;hb=HEAD#l304
mpeg2_header = (uint32_t *)(data+(header_size));
if (*mpeg2_header == 0xb8010000) // GOP_START_CODE
header_size += 4;
}
}
// See if we have the second GOP_START_CODE. Normally 31 bits == 4 bytes
// https://git.libav.org/?p=libav.git;a=blob;f=libavcodec/mpeg12enc.c;h=3376f1075f4b7582a8e4556e98deddab3e049dab;hb=HEAD#l304
if (hs + 4 <= len && RB32(data + hs) == 0x000001b8) // GOP_START_CODE
hs += 4;
n->pkt_meta = pktbuf_alloc(data, header_size);
n->pkt_meta = pktbuf_alloc(data, hs);
}
}