ffmpeg 源代码简单分析 ： av_read_frame()(三)
.pts != AV_NOPTS_VALUE &&
st->cur_pkt.dts != AV_NOPTS_VALUE &&
st->cur_pkt.pts < st->cur_pkt.dts){
av_log(s, AV_LOG_WARNING, "Invalid timestamps stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d\n",
st->cur_pkt.stream_index,
st->cur_pkt.pts,
st->cur_pkt.dts,
st->cur_pkt.size);
// av_free_packet(&st->cur_pkt);
// return -1;
}
if(s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_DEBUG, "av_read_packet stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d, duration=%d, flags=%d\n",
st->cur_pkt.stream_index,
st->cur_pkt.pts,
st->cur_pkt.dts,
st->cur_pkt.size,
st->cur_pkt.duration,
st->cur_pkt.flags);
s->cur_st = st;
st->cur_ptr = st->cur_pkt.data;
st->cur_len = st->cur_pkt.size;
if (st->need_parsing && !st->parser && !(s->flags & AVFMT_FLAG_NOPARSE)) {
st->parser = av_parser_init(st->codec->codec_id);
if (!st->parser) {
av_log(s, AV_LOG_VERBOSE, "parser not found for codec "
"%s, packets or times may be invalid.\n",
a
vcodec_get_name(st->codec->codec_id));
/* no parser available: just output the raw packets */
st->need_parsing = AVSTREAM_PARSE_NONE;
}else if(st->need_parsing == AVSTREAM_PARSE_HEADERS){
st->parser->flags |= PARSER_FLAG_COMPLETE_FRAMES;
}else if(st->need_parsing == AVSTREAM_PARSE_FULL_ONCE){
st->parser->
flags |= PARSER_FLAG_ONCE;
}
}
}
}
if(s->debug & FF_FDEBUG_TS)
av_log(s, AV_LOG_DEBUG, "read_frame_internal stream=%d, pts=%"PRId64", dts=%"PRId64", size=%d, duration=%d, flags=%d\n",
pkt->stream_index,
pkt->pts,
pkt->dts,
pkt->size,
pkt->duration,
pkt->flags);
return 0;
}
一般的码流都需要解析，这是需要调用av_paser_parse2()，它的代码如下所示：
[cpp]
//解析。例如解析264里的NAL等等
int av_parser_parse2(AVCodecParserContext *s,
AVCodecContext *avctx,
uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size,
int64_t pts, int64_t dts,
int64_t pos)
{
int index, i;
uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];
if(!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
s->next_frame_offset =
s->cur_offset = pos;
s->flags |= PARSER_FLAG_FETCHED_OFFSET;
}
if (buf_size == 0) {
/* padding is always necessary even if EOF, so we add it here */
memset(dummy_buf, 0, sizeof(dummy_buf));
buf = dummy_buf;
} else if (s->cur_offset + buf_size !=
s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
/* add a new packet descriptor */
i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
s->cur_frame_start_index = i;
s->cur_frame_offset[i] = s->cur_offset;
s->cur_frame_end[i] = s->cur_offset + buf_size;
s->cur_fram