On Tue, Nov 14, 2017 at 03:36:49PM -0800, Thierry Foucu wrote: > On Tue, Nov 14, 2017 at 3:23 PM, Derek Buitenhuis < > derek.buitenh...@gmail.com> wrote: > > > On 11/14/2017 10:11 PM, Sasi Inguva wrote: > > > I don't know if the patch can be made more generic to work for all > > > demuxers, because this patch requires that PTS of all packets be > > available > > > in the header. The other route is to make it very specific to codecs > > with > > > B-frames. > > > > All PTS may not be available in MP4 either, in the live profile fragmented > > MP4 case, no? I am not familiar enough with the fragmented MP4 demuxing > > code > > say whether we seek to each fragment and make it available or not. I assume > > you've tested such a case, or can (or know the fragment code)? > > > > It's feasible to restrict it to codecs, I suppose. > > > > >> You do not appear to be restricting this to one specific codec, or even > > >> codecs > > >> with B-frames. > > >> > > >> I can make it specific to only H264 / H265. > > > > The GOP structure should be applicable to most MPEG codecs, I think. > > > > > It is true that the patch will fail to compute the correct delay in lots > > of > > > cases. However the consequence of wrongly computing the has_b_frames is > > > pretty benign. It only increases the buffer size held for PTS > > reordering. > > > I can put a max-value check on the computed video_delay here. So in my > > > opinion, we won't see fatal regressions where a file is not able to be > > > decoded / played. > > > > It's true it's likely benign, but it's not exactly a "fix" either... > > > > From a user perspective, it's kinda possible to work around it "properly" > > (I use that term loosely here) by decoding enough frames to fill the max > > DPB for a given codec (e.g. 16 for H.264) in avformat_find_stream_info > > (or in a user's code if they don't use that function), isn't it? Though, > > I feel that particular fix won't be welcomed with open arms, due to a > > ~16x 'slow down' in probing. > > > > > One option i asked on IRC was to use the spec for max DPB when the bitstream > restriction flag was not set. > But people were worry about low latency usage. > Normally, if the bitstream restriction flag is not set, the DPB should be > set based on the spec, even if there is no B frames. > But in some case, it will be 16 frame and this could increase then the low > latency.
it could also increase memory requirements substantially [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Avoid a single point of failure, be that a person or equipment.
signature.asc
Description: Digital signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
