[FFmpeg-devel] [PATCH v3 0/7] Merge lazy filter initialization in ffmpeg CLI

Michael Niedermayer michael at niedermayer.cc
Thu Mar 2 21:31:53 EET 2017


On Thu, Mar 02, 2017 at 06:27:29PM +0100, wm4 wrote:
> On Thu, 2 Mar 2017 17:12:04 +0100
> Michael Niedermayer <michael at niedermayer.cc> wrote:
> 
> > On Thu, Mar 02, 2017 at 02:37:09PM +0100, wm4 wrote:
> > > On Thu, 2 Mar 2017 14:03:18 +0100
> > > Michael Niedermayer <michael at niedermayer.cc> wrote:
> > >   
> > > > On Thu, Mar 02, 2017 at 09:53:02AM +0100, wm4 wrote:  
> > > > > These patches merge the previously skipped Libav commits, which made
> > > > > avconv lazily initialize libavfilter graphs. This means the filters
> > > > > are initialized with the actual output format, instead of whatever
> > > > > libavformat reports.
> > > > > 
> > > > > It's a prerequisite to making hardware decoding support saner, as
> > > > > hardware decoders will output a different pixfmt than the software
> > > > > format reported by libavformat. This can be seen on ffmpeg_qsv.c
> > > > > and ffmpeg_cuvid.c, which don't lose any functionality, even though
> > > > > half of the code is removed.
> > > > > 
> > > > > There are some differences in how ffmpeg.c and avconv.c filter-flow
> > > > > works. Also, avconv.c doesn't have sub2video. Relatively intrusive
> > > > > changes were required.
> > > > > 
> > > > > I will push this tomorrow, except if critical failures are found.    
> > > > 
> > > > I think the patchset improved in terms of regressions but there are
> > > > still several
> > > >   
> > [...]
> > >  
> > > > 
> > > > also this code crashes with some private files:
> > > > ==7506== Process terminating with default action of signal 11 (SIGSEGV)
> > > > ==7506==  Access not within mapped region at address 0x8
> > > > ==7506==    at 0x471529: av_buffersink_get_frame_rate (buffersink.c:193)
> > > > ==7506==    by 0x435B54: init_output_stream_encode (ffmpeg.c:3217)
> > > > ==7506==    by 0x4364A8: init_output_stream (ffmpeg.c:3351)
> > > > ==7506==    by 0x42E4DB: reap_filters (ffmpeg.c:1428)
> > > > ==7506==    by 0x43AA44: transcode_step (ffmpeg.c:4452)
> > > > ==7506==    by 0x43AB28: transcode (ffmpeg.c:4496)
> > > > ==7506==    by 0x43B2FD: main (ffmpeg.c:4701)  
> > > 
> > > I don't know if you're shitting me on purpose. I can't fix what I can't
> > > reproduce, and you never gave me access to those files. Fix it yourself
> > > if you think it's important. Seriously, what is this.  
> > 
> > I ofered access to this file to someone wanting to work on this
> > previously
> > "If this backtrace is not sufficient i can share the file privatly
> >  with someone who wants to work on fixing this"
> > 
> > Noone asked for the file, if you want to work on this and keep the file
> > private, i can share it with you.
> > 
> > Its not nice from you to ignore my ofer and then attack me pretending
> > there was no such offer
> 
> OK, I missed that part. Sorry. I guess I overlooked it when I tried to
> collect all the new test cases and tried to find the required samples
> (for which you only provided a path on your local disk, and I had to
> look them up from the ticker number in that path). So I apologize, but
> I'm still grumpy.
> 
> Anyway, _please_ don't report bugs to me in the future without providing
> a direct sample link (sure, you can do it privately if necessary).
> 

> In the mean time, I somehow expected you'd provide me a sample for the
> case above (in private), since you know that I obviously want and don't
> have it, but you didn't yet. Why make me ask.

because i have no permission to share the file unless its neccessary.


> 
> Btw., I've tested every single case you pointed out and which I could
> test.

you missed one case it seems
./ffmpeg -skip_frame nokey -ss 20  -i ~/tickets/2024/dvbsubtest.ts -qscale 2  -scodec dvbsub -t 6   -an file.ts

displays fewer subtitles than before the patchset, i did report this
case previously


> 
> > 
> > >   
> > > > This one produces a silent audio channel as previous patchsets did too
> > > > ./ffmpeg -i ~/tickets/1726/Mono.thd out.wav  
> > > 
> > > While libavformat signals a mono channel configuration, the decoder
> > > actually outputs stereo, with one channel muted. You can reproduce this
> > > with current master ffmpeg too by adding "-ac 2". If this is a bug,
> > > then it's merely an old bug that is made more obvious by this patch,
> > > rather than introducing it.
> > > 
> > > I don't know why you could not determine this yourself. It would have
> > > been easy to check.  
> > 
> > Ive a huge amount of things to do, and analyzing differences is alot
> > of work, i stated that previously yet you keep attacking me, and i
> > tried to do some light analysis on some things to help a bit but could
> > not on all
> 
> This is not the first time you're implying that your time is somehow
> more valuable than mine.

iam not implying that.
what iam implying is that if a person or group wants something its
theirs to do the work. Thats especially true in FLOSS
you seem to expect me to also want to work on the same things you
want to work on.


> 
> Anyway, I realize I might have misinterpreted your efforts. If the
> failing examples you point out don't need to be fixed and are not an
> absolute requirement for the patches to get a passing mark, but are
> only provided by you as some sort of "help", then that's totally fine
> with me.

yes, iam just trying to help, what people do with these cases is up
to them.



[...]

> In this case it was mostly not so good timing, but you have to admit
> that coming up with subtle transcoding differences of fuzzed files is
> almost surely bullshit. Most of the failures were corner cases. I might
> have overreacted because I interpreted it so that you meant every issue
> you pointed out was a blocker. Yeah, I apologize, but I'm still a bit
> grumpy. I appreciate that you want to do some quality control and that
> you want to help out, but I perceived it a bit different.



> 
> So my advice to you is: ignore issues that are probably obscure and not
> immediate problems, and for issues that should be fixed make quality bug
> reports. Don't let the merger who's just trying to get things done do
> it.

i can test and report what i find or if the community wants me to
stop testing i can stop testing. I already spend time on analyzing
the issues lightly and thats already beyond the time i have available.



[...]
> > everyone of them will pretend its a surprise and they didnt see it
> > comming.
> 
> Well, you already announced that you'd leave the project a few months

no, i did not do that, i resigned as leader, and multiple people asked
me to stay in the project as a developer. But it becomes less and less
enjoyable really thanks to the endless attacks.

there also was a IRC conference and we by consensus choose a initial
vote comittee that we then extended by adding more people multiple
times.
That comittee should more or less match the active developers and is
what leads the project ATM.
you could simplify that "slightly incorrectly" as in saying the
active developers lead the project.

anyway, ive a headache and if anything in the mail sounds offensive
i can assure you its unintended

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Complexity theory is the science of finding the exact solution to an
approximation. Benchmarking OTOH is finding an approximation of the exact
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