On Mon, Apr 25, 2022 at 2:33 PM Jan Ekström <jee...@gmail.com> wrote: > > On Mon, Apr 25, 2022 at 1:36 PM Jan Ekström <jee...@gmail.com> wrote: > > > > On Tue, Apr 19, 2022 at 11:06 PM Marton Balint <c...@passwd.hu> wrote: > > > > > > > > > > > > On Tue, 19 Apr 2022, Jan Ekström wrote: > > > > > > > On Tue, Apr 19, 2022 at 1:13 PM Jan Ekström <jee...@gmail.com> wrote: > > > >> > > > >> On Tue, Apr 19, 2022 at 3:00 AM Marton Balint <c...@passwd.hu> wrote: > > > >> > > > > >> > > > > >> > > > > >> > On Thu, 14 Apr 2022, Jan Ekström wrote: > > > >> > > > > >> > > On Mon, Apr 11, 2022 at 1:50 PM Jan Ekström <jee...@gmail.com> > > > >> > > wrote: > > > >> > >> > > > >> > >> From: Jan Ekström <jan.ekst...@24i.com> > > > >> > >> > > > >> > >> Additionally, they should not be probed, as this is essentially > > > >> > >> various types of binary data. > > > >> > >> > > > >> > >> Signed-off-by: Jan Ekström <jan.ekst...@24i.com> > > > >> > >> --- > > > >> > > > > > >> > > Ping. > > > >> > > > > > >> > > Basically this checks if we have an unknown stream with a private > > > >> > > stream type still at the end of the per-stream loop in PMT parsing, > > > >> > > and then cancels the stop of parsing that usually occurs as a PMT > > > >> > > is > > > >> > > hit. Instead the logic will continue parsing further. When an SDT > > > >> > > is > > > >> > > then found and a PMT for that program has already been received, it > > > >> > > will then stop header reading at that point. > > > >> > > > > >> > But why does it matter when the initial parsing is stopped? I mean it > > > >> > stops at the first PMT right now, nobody expects it to find all the > > > >> > programs and all the streams or all the stream codecs/parameters. > > > >> > > > > >> > I am saying, that ideally, the ts->stop_parse magic should not be > > > >> > needed > > > >> > to be changed to fix your issue and when an SDT is detected with the > > > >> > broadcast descriptor that should stop any existing data stream > > > >> > parsing. Do > > > >> > you know why it does not work like that? > > > >> > > > > >> > > > >> If the codec is unknown after header parsing, the general parsing > > > >> logic is utilized to probe which codec is possibly in that unknown > > > >> stream, and thus more data is read from that stream, which can cause > > > >> further delays. > > > >> > > > >> If the codec is known as data, it leads to no such result. > > > >> > > > >> Basically, the idea is to figure out whether a stream is a data stream > > > >> or not during header parsing, if possible. > > > >> > > > > > > > > Just double-checked and the difference is whether > > > > max_stream_analyze_duration gets utilized in > > > > libavformat/demux.c::avformat_find_stream_info . > > > > > > > > If a stream is marked as unknown, it will get checked for longer. If > > > > it is marked as a known "codec" it gets through quicker. > > > > > > The part of the patch which parses the SDT and sets the codec is fine. > > > But the fact that you have to set the codec during mpegts_read_header > > > to make it stop parsing definitely looks like some bug in some code > > > somewhere. It should be enough to set the codec sometime later in > > > mpegts_read_packet() (which is called during avformat_find_stream_info()) > > > > > > Or to make it even more strange: comment out handle_packets() in > > > mpegts_read_header. And it will work just fine. So if nothing is parsed > > > in mpegts_read_header then it works. If something is parsed, then it does > > > not. Kind of unexpected... > > > > > > Regards, > > > Marton > > > > Hi, > > > > So I poked at this again and did the changes you requested. The result > > is that if the "continue parsing until SDT if you have these sorts of > > streams in-band" logic is removed, it leads to the FATE test ending up > > with the result of "codec_name=unknown". Which makes the test rather > > useless as it doesn't actually show that the stream is noted as a data > > stream. Additionally, I thought the logic made sense since as much as > > I dislike having information outside of PMT being utilized for PMT > > purposes, that is effectively what this SDT descriptor is utilized > > for. Given I specifically limited this logic to unknown streams within > > a specific stream identifier range, the effect of this change would > > have been far-from-global as well. > > > > I have a hunch that information is copied from the lavf-internal codec > > context to codecpar at one point, and then no further synchronization > > is attempted. > > So, when checking the following diff: > > diff --git a/libavformat/demux.c b/libavformat/demux.c > index ad7b5dbf83..6e483acb10 100644 > --- a/libavformat/demux.c > +++ b/libavformat/demux.c > @@ -2909,6 +2909,11 @@ int avformat_find_stream_info(AVFormatContext > *ic, AVDictionary **options) > FFStream *const sti = ffstream(st); > const char *errmsg; > > + av_log(ic, AV_LOG_VERBOSE, > + "stream %u (%sinitialized), codec context codec: %s, > codecpar codec: %s\n", > + i, sti->avctx_inited ? "" : "not ", > + avcodec_get_name(sti->avctx->codec_id), > avcodec_get_name(st->codecpar->codec_id)); > + > /* if no packet was ever seen, update context now for > has_codec_parameters */ > if (!sti->avctx_inited) { > if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && > > > ..the result was that: > - codec context was already noted as initialized > - the codecpar codec was bin_data > - the codec context one was still none. > > I hacked it to do the update in case of sti->need_context_update in > the if visible in the diff, and it led to the update of the end > result. > > Thus it seems like read_frame_internal - or some other function should > probably check whether a context update was requested by the demuxer. > That way it might be possible to stop the processing earlier as well. >
After further checking, it seems like the MPEG-TS demuxer never returns a packet for the data stream looking at the results from ff_read_packet/read_frame_internal, which explains why the already existing sti->need_context_update logic within read_frame_internal does not get hit. Jan _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".