Aman Gupta: > On Wed, Apr 10, 2019 at 1:00 AM Hendrik Leppkes <h.lepp...@gmail.com> wrote: > >> On Wed, Apr 10, 2019 at 9:55 AM Aman Gupta <ffm...@tmm1.net> wrote: >>> >>> On Tue, Apr 9, 2019 at 9:49 PM Hendrik Leppkes <h.lepp...@gmail.com> >> wrote: >>> >>>> On Wed, Apr 10, 2019 at 2:21 AM Aman Gupta <ffm...@tmm1.net> wrote: >>>>> >>>>> From: Aman Gupta <a...@tmm1.net> >>>>> >>>>> Previously, the initial seek position was recorded into >>>>> old_offset at the beginning of avformat_find_stream_info(), >>>>> and passed into estimate_timings(). In the case of mpegts >>>>> with a known filesize, it was further passed into >>>>> estimate_timings_from_pts() which called avio_seek(SEEK_SET) >>>>> after doing its timing related seeks. (Interestingly, this >>>>> seeked all the way back to the initial position before >>>>> the probe, rather than only back before the timing >>>>> related seeks to the end of the file). >>>>> >>>>> With this commit, we pull the avio_seek() out of the mpegts >>>>> specific code-path and unconditionally seek all streams back >>>>> to their original position after probing is complete. >>>>> >>>>> This effectively prevents data that is consumed during >>>>> avformat_find_stream_info() from being discarded, so packets >>>>> contained at the beginning of a file are still passed back >>>>> to the user for playback. >>>>> >>>> >>>> I don't think I ever had a case where data was apparently lost from >>>> the beginning of the stream. Can you give examples of what this fixes? >>> >>> >>> Perhaps I'm missing something. >>> >>> If I see the debug log message "After avformat_find_stream_info() pos: >>> 1000000 bytes seeks:0", are the packets from the first megabyte of the >>> file still returned from API? Maybe they are being cached somewhere and I >>> did not notice. >>> >> >> As far as I know, the packets read during stream info probing are >> being cached in a buffer and returned to the caller on av_read_frame. > > > Okay that seems to be the missing piece. If someone can point me to where > this buffer is in the code, that would be helpful. > The packet queues are in the AVFormatInternal struct and the packets are put there via ff_packet_list_put. The most interesting thing for you might be ff_read_packet.
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