Hi 2009/6/30 Baptiste Coudurier <[email protected]>
> Hi Zhentan, > > zhentan feng wrote: > > Hi > > > > 2009/6/29 Baptiste Coudurier <[email protected]> > > > >> spyfeng wrote: > >>> Author: spyfeng > >>> Date: Sat Jun 27 15:35:59 2009 > >>> New Revision: 4533 > >>> > >>> Log: > >>> set correct pos when cannot get pos from ff_fetch_timestamp(). > >>> > >>> Modified: > >>> seek_api/parser.c > >>> > >>> Modified: seek_api/parser.c > >>> > >> > ============================================================================== > >>> --- seek_api/parser.c Sat Jun 27 15:28:08 2009 (r4532) > >>> +++ seek_api/parser.c Sat Jun 27 15:35:59 2009 (r4533) > >>> @@ -188,6 +188,8 @@ int av_parser_parse2(AVCodecParserContex > >>> if (index < 0) > >>> index = 0; > >>> s->cur_offset += index; > >>> + if (s->pos == -1) > >>> + s->pos = s->last_pos + index; > >>> return index; > >>> } > >> Can you explain why this change is needed ? It seems wrong to me. > >> > >> The goal is for getting the correct pkt->pos when call av_read_frame(). > > > > consider the attached two log files below. I added some log info when > > av_parser_parse2() is called in libavformait/utils.c > > logpf2.txt is the original outputs and logpf3.txt is the new outputs. > > > > I select some lines from logf2.txt. > > for example, the first frame of stream index = 1 is: > > [mpeg @ 0x9c43440]av_read_frame_internal stream=1, pts=45000, dts=45000, > > size=208, flags=1, pos=2048 > > > > then the second frame is > > [mpeg @ 0x9c43440]av_read_frame_internal stream=1, pts=47351, dts=47351, > > size=209, flags=1, pos=-1 > > > > actually, we can calculate the second frame pos by the last_pos. > > If keep the frame as -1, when find the keyframe by index entries, the > index > > entries pos is -1, we cannot seek there. > > Yes, pos must be set to the PES packet pos to be able to seek there and > retrieve correct pts/dts for the frame. > Example below: > > > > > > > ------------------------------------------------------------------------ > > > > Input #0, mpeg, from 'tests/data/b-lavf.mpg': > > Duration: 00:00:01.01, start: 0.500000, bitrate: 2975 kb/s > > Stream #0.0[0x1e0], 1/90000: Video: mpeg1video, yuv420p, 352x288 [PAR > 1:1 DAR 11:9], 1/25, 104857 kb/s, 25 tbr, 90k tbn, 25 tbc > > Stream #0.1[0x1c0], 1/90000: Audio: mp2, 44100 Hz, mono, s16, 64 kb/s > > Output #0, null, to '/dev/null': > > Stream #0.0, 1/90000: Video: rawvideo, yuv420p, 352x288 [PAR 1:1 DAR > 11:9], 1/25, q=2-31, 200 kb/s, 90k tbn, 25 tbc > > Stream #0.1, 1/90000: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s > > Stream mapping: > > Stream #0.0 -> #0.0 > > Stream #0.1 -> #0.1 > > Press [q] to stop encoding > > [mpeg @ 0x9c43440]mpeg add index stream_index=0, pos = 30, dts = 41400 > > [mpeg @ 0x9c43440]av_read_packet stream=0, pts=45000, dts=41400, > size=2002, flags=0, pos = 30 > > [mpeg @ 0x9c43440]mpeg add index stream_index=1, pos = 2048, dts = 45000 > > [mpeg @ 0x9c43440]av_read_packet stream=1, pts=45000, dts=45000, > size=2037, flags=0, pos = 2048 > > pos is set here. > > > [mpeg @ 0x9c43440]pkt pos:2048, st->parser->pos:2048 > > [mpeg @ 0x9c43440]stream_index 1, the frame_offset = 2048 > > [mpeg @ 0x9c43440]av_read_frame_internal stream=1, pts=45000, dts=45000, > size=208, flags=1, pos=2048 > > [mpeg @ 0x9c43440]pkt pos:-1, st->parser->pos:-1 > > [mpeg @ 0x9c43440]stream_index 1, the frame_offset = 2256 > > > > > [mpeg @ 0x9c43440]av_read_frame_internal stream=1, pts=47351, dts=47351, > size=209, flags=1, pos=-1 > > [mpeg @ 0x9c43440]pkt pos:-1, st->parser->pos:-1 > > [mpeg @ 0x9c43440]stream_index 1, the frame_offset = 2465 > > Pos must be 2048 as well. > fixed , please see r4550 patch. > > [...] -- Best wishes~ _______________________________________________ FFmpeg-soc mailing list [email protected] https://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-soc
