On Tue, Oct 4, 2016 at 4:44 PM, James Almer <jamr...@gmail.com> wrote: > On 10/4/2016 11:35 AM, Hendrik Leppkes wrote: >> On Tue, Oct 4, 2016 at 4:32 PM, wm4 <nfx...@googlemail.com> wrote: >>> On Tue, 4 Oct 2016 14:15:03 +0200 >>> Michael Niedermayer <mich...@niedermayer.cc> wrote: >>> >>>> On Tue, Oct 04, 2016 at 01:52:02PM +0200, Hendrik Leppkes wrote: >>>>> On Tue, Oct 4, 2016 at 1:44 PM, Hendrik Leppkes <h.lepp...@gmail.com> >>>>> wrote: >>>>>> On Tue, Oct 4, 2016 at 1:23 PM, Michael Niedermayer >>>>>> <mich...@niedermayer.cc> wrote: >>>>>>> On Tue, Oct 04, 2016 at 08:41:42AM +0200, Hendrik Leppkes wrote: >>>>>>>> On Tue, Oct 4, 2016 at 4:05 AM, Michael Niedermayer >>>>>>>> <mich...@niedermayer.cc> wrote: >>>>>>>>> On Sat, Oct 01, 2016 at 04:15:45PM +0200, Hendrik Leppkes wrote: >>>>>>>>>> Decoders have previously not used AVFrame.pts, and with the upcoming >>>>>>>>>> deprecation of pkt_pts (in favor of pts), this would lead to an >>>>>>>>>> errorneous >>>>>>>>>> interpration of timestamps. >>>>>>>>> >>>>>>>>> I probably misunderstand the commit message but >>>>>>>>> If code is changed in a user application that cannot really lift >>>>>>>>> some blockage from changing a lib. >>>>>>>>> a lib can only change in an incompaible way with (deprecation and) >>>>>>>>> major version bump. >>>>>>>>> >>>>>>>> >>>>>>>> The lib never did what this code suggests it did, not that I remember >>>>>>>> (so at least not for a long long time). >>>>>>> >>>>>>> release/2.0 with >>>>>>> >>>>>>> diff --git a/libavcodec/utils.c b/libavcodec/utils.c >>>>>>> index 29d5492..57c8d50 100644 >>>>>>> --- a/libavcodec/utils.c >>>>>>> +++ b/libavcodec/utils.c >>>>>>> @@ -2008,7 +2008,7 @@ int attribute_align_arg >>>>>>> avcodec_decode_video2(AVCodecContext *avctx, AVFrame *pi >>>>>>> avci->to_free.extended_data = avci->to_free.data; >>>>>>> memset(picture->buf, 0, sizeof(picture->buf)); >>>>>>> } >>>>>>> - >>>>>>> +av_assert0(picture->pts == 0 || picture->pts == AV_NOPTS_VALUE); >>>>>>> avctx->frame_number++; >>>>>>> av_frame_set_best_effort_timestamp(picture, >>>>>>> guess_correct_pts(avctx, >>>>>>> >>>>>>> causes many tests to fail, indicating that AVFrame.pts was set for >>>>>>> several video decoders, the ffmpeg code is audio decoder specific >>>>>>> and i failed to find a case where it was triggered, i tried IIRC 3 >>>>>>> or so checkouts from the past >>>>>>> >>>>>>> so AVFrame.pts was maybe never set for decoding audio but it was set >>>>>>> for video >>>>>> >>>>>> Can you extend the test to add "|| picture->pts == picture->pkt_pts"? >>>>>> Because thats what it would be set to after the merge. A quick check >>>>>> in the 2.0 code base looks like some decoders did set that, but to the >>>>>> exact same value as pkt_pts (which is what the merge is proposing >>>>>> right now as well) >>>>>> >>>>> >>>>> And I found this (after 2.0): >>>>> http://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=a1c5cc429d99216406170eac7e8352860076d3e8 >>>>> >>>>> Which apparently set pts for mpeg4 to a number parsed from the >>>>> bitstream, entirely uncorrelated to container or audio timestamps, so >>>>> using them would have been rather impractical for any real use-cases. >>>> >>>> They can be usfull, some random examples: >>>> >>>> playing MPEG4-ES with timing stored from the bitstream (assuming there >>>> is no demuxer lib used that is capable to extract them) >>>> >>>> forensics, raw video stream could have its timing >>>> recovered, a video with manipulated container timestamps could be >>>> detected. >>>> >>>> error correction, if the container level timestamps are lost or >>>> corrupted the stream level ones can be used to recreate them >>>> >>>> There may be more, these are just some of the top of my head, >>>> not your mainstream multimedia player stuff maybe but they arent >>>> useless >>>> >>>> [...] >>>> >>> >>> They don't belong into the AVFrame.pts field, though. >> >> And they don't go in there anymore right now, so thats that. >> >> The real question is, what do we do about this merge now? >> Can we set AVFrame.pts to the same value as AVFrame.pkt_pts safely, >> considering it was unused in the current ABI/API, or would that be >> considered an API break and we better delay this change until the next >> major? >> >> - Hendrik > > Delaying it could result in further merges becoming technically wrong, > or at least require extra manual changes for them to not misbehave in > our tree. > > IMO merge it now, and if needed/preferred, we could make sure it > doesn't make it to 3.2 >
Last call for any actual and clear objections to going forward with this route. I would like to get merging a bunch over the weekend so we get some progress here. - Hendrik _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
