> -----Original Message----- > From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf > Of Gyan > Sent: Wednesday, July 24, 2019 12:28 > To: ffmpeg-devel@ffmpeg.org > Subject: Re: [FFmpeg-devel] [PATCH, v3] fftools/ffmpeg_filter: add - > autoscale to disable/enable the default scale > > > > On 24-07-2019 08:15 AM, Fu, Linjie wrote: > >> -----Original Message----- > >> From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On > Behalf > >> Of Gyan > >> Sent: Wednesday, July 24, 2019 00:49 > >> To: ffmpeg-devel@ffmpeg.org > >> Subject: Re: [FFmpeg-devel] [PATCH, v3] fftools/ffmpeg_filter: add - > >> autoscale to disable/enable the default scale > >> > >> > >> > >> On 22-07-2019 01:40 PM, Fu, Linjie wrote: > >>>> -----Original Message----- > >>>> From: ffmpeg-devel [mailto:ffmpeg-devel-boun...@ffmpeg.org] On > >> Behalf > >>>> Of Gyan > >>>> Sent: Saturday, July 20, 2019 13:29 > >>>> To: ffmpeg-devel@ffmpeg.org > >>>> Subject: Re: [FFmpeg-devel] [PATCH, v3] fftools/ffmpeg_filter: add - > >>>> autoscale to disable/enable the default scale > >>>>> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi > >>>>> index cd35eb49c8..99121b6981 100644 > >>>>> --- a/doc/ffmpeg.texi > >>>>> +++ b/doc/ffmpeg.texi > >>>>> +@item -autoscale > >>>>> +Automatically scale the video according to the resolution of first > frame. > >>>>> +Enabled by default, use @option{-noautoscale} to disable it. When > >>>> autoscale is > >>>>> +disabled, all output frames might not be in the same resolution and > >> may > >>>> require > >>>>> +some additional explicit processing according to your final > >>>> rendering/output > >>>>> +destination. Disabling autoscale may not work in all situations. > >> Therefore, > >>>> it > >>>>> +is not recommended to disable it unless you really know what you > are > >>>> doing. > >>>>> +Disable autoscale at your own risk. > >>>> Since the auto scaling happens at the end of the graph, what may the > >>>> "additional explicit processing" be? > >>> Vpp processing may not be influenced, a warning in transcode is needed. > >>> The expression seems to be improper, how about: > >>> > >>> "When autoscale is disabled, all output frames of filter graph might not > be > >> in the same > >>> resolution and may be inadequate for encoder/muxer." > >>> > >>> or other suggestions? > >>> > >>>>> @@ -3640,6 +3642,12 @@ const OptionDef options[] = { > >>>>> { "autorotate", HAS_ARG | OPT_BOOL | OPT_SPEC | > >>>>> OPT_EXPERT | OPT_INPUT, > >>>>> { .off = > >>>> OFFSET(autorotate) }, > >>>>> "automatically insert correct rotate filters" }, > >>>>> + { "autoscale", HAS_ARG | OPT_BOOL | OPT_SPEC | > >>>>> + OPT_EXPERT | OPT_INPUT, > >>>>> { .off = > >>>> OFFSET(autoscale) }, > >>>>> + "automatically insert a scale filter at the end of the filter > >>>>> graph if > a > >>>> resolution" > >>>>> + "change is detected. This ensures all frames are the same > >> resolution > >>>> as the first frame" > >>>>> + "when they leave the filter chain (this option is enabled by > >> default)." > >>>>> + "If disabled, some encoders/muxers may not support this > mode."}, > >>>> Which muxers can detect or check for prop changes within coded > >>>> bitstreams? Which encoders are known to be able to handle > >>>> changing resolution? > >>> It's not supported currently (even in libvpx-vp9, since vp9 supports > >> dynamic resolution in spec). > >>> I don't intend to be so absolutely in doc, will it be better for you to > modify > >> like: > >>> "If disabled, encoders/muxers won't support this mode currently." > >> So other than `-c:v rawvideo -f rawvideo`, there is no combination > >> that supports changing frame sizes? > > I didn't check all encoders. > > But since the resolution changing is detectable, some additional reinit > procedures > > can be added to change resolution at IDR frame and make the encoder > works. > > > They could, but as of now, which encoder + muxer combinations are > **known** to work? > As far as I tried, no. (pipeline failed in libx264, garbage exists in libx265 and libvpx-vp9 ) _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
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