[FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -autoscale to disable/enable the default scale
Gyan Doshi
ffmpeg at gyani.pro
Mon Feb 17 20:10:14 EET 2020
On 17-02-2020 11:29 pm, Fu, Linjie wrote:
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
>> Gyan Doshi
>> Sent: Tuesday, February 18, 2020 01:44
>> To: ffmpeg-devel at ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -autoscale
>> to disable/enable the default scale
>>
>>
>>
>> On 17-02-2020 11:07 pm, Fu, Linjie wrote:
>>>> -----Original Message-----
>>>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
>>>> Gyan Doshi
>>>> Sent: Tuesday, February 18, 2020 01:33
>>>> To: ffmpeg-devel at ffmpeg.org
>>>> Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -
>> autoscale
>>>> to disable/enable the default scale
>>>>
>>>>
>>>>
>>>> On 17-02-2020 10:57 pm, Fu, Linjie wrote:
>>>>>> -----Original Message-----
>>>>>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf
>> Of
>>>>>> Gyan Doshi
>>>>>> Sent: Tuesday, February 18, 2020 00:53
>>>>>> To: ffmpeg-devel at ffmpeg.org
>>>>>> Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -
>>>> autoscale
>>>>>> to disable/enable the default scale
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 17-02-2020 09:13 pm, Fu, Linjie wrote:
>>>>>>>> -----Original Message-----
>>>>>>>> From: Fu, Linjie <linjie.fu at intel.com>
>>>>>>>> Sent: Sunday, February 16, 2020 00:13
>>>>>>>> To: ffmpeg-devel at ffmpeg.org
>>>>>>>> Cc: Fu, Linjie <linjie.fu at intel.com>; Eoff, Ullysses A
>>>>>>>> <ullysses.a.eoff at intel.com>
>>>>>>>> Subject: [PATCH] fftools/ffmpeg_filter: add -autoscale to
>>>> disable/enable
>>>>>> the
>>>>>>>> default scale
>>>>>>>>
>>>>>>>> Currently, ffmpeg inserts scale filter by default in the filter graph
>>>>>>>> to force the whole decoded stream to scale into the same size with
>> the
>>>>>>>> first frame. It's not quite make sense in resolution changing cases if
>>>>>>>> user wants the rawvideo without any scale.
>>>>>>>>
>>>>>>>> Using autoscale/noautoscale as an output option to indicate
>> whether
>>>> auto
>>>>>>>> inserting the scale filter in the filter graph:
>>>>>>>> -noautoscale or -autoscale 0:
>>>>>>>> disable the default auto scale filter inserting.
>>>>>>>>
>>>>>>>> ffmpeg -y input.mp4 out1.yuv -noautoscale out2.yuv -autoscale 0
>>>>>> out3.yuv
>>>>>>>> Update docs.
>>>>>>>>
>>>>>>>> Signed-off-by: U. Artie Eoff <ullysses.a.eoff at intel.com>
>>>>>>>> Signed-off-by: Linjie Fu <linjie.fu at intel.com>
>>>>>>>> ---
>>>>>>>> doc/ffmpeg.texi | 16 ++++++++++++----
>>>>>>>> fftools/ffmpeg.h | 3 +++
>>>>>>>> fftools/ffmpeg_filter.c | 2 +-
>>>>>>>> fftools/ffmpeg_opt.c | 5 +++++
>>>>>>>> 4 files changed, 21 insertions(+), 5 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
>>>>>>>> index 29753f0..aebafb3 100644
>>>>>>>> --- a/doc/ffmpeg.texi
>>>>>>>> +++ b/doc/ffmpeg.texi
>>>>>>>> @@ -734,10 +734,6 @@ ffmpeg -dump_attachment:t "" -i INPUT
>>>>>>>> Technical note -- attachments are implemented as codec extradata,
>>>> so
>>>>>> this
>>>>>>>> option can actually be used to extract extradata from any stream,
>> not
>>>>>> just
>>>>>>>> attachments.
>>>>>>>> -
>>>>>>>> - at item -noautorotate
>>>>>>>> -Disable automatically rotating video based on file metadata.
>>>>>>>> -
>>>>>>>> @end table
>>>>>>>>
>>>>>>>> @section Video Options
>>>>>>>> @@ -819,6 +815,18 @@ Create the filtergraph specified by
>>>>>> @var{filtergraph}
>>>>>>>> and use it to
>>>>>>>> filter the stream.
>>>>>>>>
>>>>>>>> This is an alias for @code{-filter:v}, see the @ref{filter_option,,-
>> filter
>>>>>> option}.
>>>>>>>> +
>>>>>>>> + at item -autorotate
>>>>>>>> +Automatically rotate the video according to file metadata. Enabled
>> by
>>>>>>>> +default, use @option{-noautorotate} to disable it.
>>>>>>>> +
>>>>>>>> + at 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 of filter graph might not be in the same
>>>>>>>> resolution
>>>>>>>> +and may be inadequate for some encoder/muxer. Therefore, it is
>> not
>>>>>>>> recommended
>>>>>>>> +to disable it unless you really know what you are doing.
>>>>>>>> +Disable autoscale at your own risk.
>>>>>>>> @end table
>>>>>>>>
>>>>>>>> @section Advanced Video options
>>>>>>>> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
>>>>>>>> index 7b6f802..8beba6c 100644
>>>>>>>> --- a/fftools/ffmpeg.h
>>>>>>>> +++ b/fftools/ffmpeg.h
>>>>>>>> @@ -230,6 +230,8 @@ typedef struct OptionsContext {
>>>>>>>> int nb_time_bases;
>>>>>>>> SpecifierOpt *enc_time_bases;
>>>>>>>> int nb_enc_time_bases;
>>>>>>>> + SpecifierOpt *autoscale;
>>>>>>>> + int nb_autoscale;
>>>>>>>> } OptionsContext;
>>>>>>>>
>>>>>>>> typedef struct InputFilter {
>>>>>>>> @@ -479,6 +481,7 @@ typedef struct OutputStream {
>>>>>>>> int force_fps;
>>>>>>>> int top_field_first;
>>>>>>>> int rotate_overridden;
>>>>>>>> + int autoscale;
>>>>>>>> double rotate_override_value;
>>>>>>>>
>>>>>>>> AVRational frame_aspect_ratio;
>>>>>>>> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
>>>>>>>> index 40cc4c1..46c8ea8 100644
>>>>>>>> --- a/fftools/ffmpeg_filter.c
>>>>>>>> +++ b/fftools/ffmpeg_filter.c
>>>>>>>> @@ -469,7 +469,7 @@ static int
>>>>>> configure_output_video_filter(FilterGraph
>>>>>>>> *fg, OutputFilter *ofilter,
>>>>>>>> if (ret < 0)
>>>>>>>> return ret;
>>>>>>>>
>>>>>>>> - if (ofilter->width || ofilter->height) {
>>>>>>>> + if ((ofilter->width || ofilter->height) && ofilter->ost->autoscale) {
>>>>>>>> char args[255];
>>>>>>>> AVFilterContext *filter;
>>>>>>>> AVDictionaryEntry *e = NULL;
>>>>>>>> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
>>>>>>>> index 12d4488..a6f4216 100644
>>>>>>>> --- a/fftools/ffmpeg_opt.c
>>>>>>>> +++ b/fftools/ffmpeg_opt.c
>>>>>>>> @@ -1405,6 +1405,8 @@ static OutputStream
>>>>>>>> *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
>>>>>>>> ost->encoder_opts = filter_codec_opts(o->g->codec_opts,
>> ost-
>>>>>>> enc-
>>>>>>>>> id, oc, st, ost->enc);
>>>>>>>> MATCH_PER_STREAM_OPT(presets, str, preset, oc, st);
>>>>>>>> + ost->autoscale = 1;
>>>>>>>> + MATCH_PER_STREAM_OPT(autoscale, i, ost->autoscale, oc, st);
>>>>>>>> if (preset && (!(ret = get_preset_file_2(preset, ost->enc-
>>> name,
>>>>>> &s))))
>>>>>>>> {
>>>>>>>> do {
>>>>>>>> buf = get_line(s);
>>>>>>>> @@ -3650,6 +3652,9 @@ 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_OUTPUT, { .off =
>>>>>>>> OFFSET(autoscale) },
>>>>>>>> + "automatically insert a scale filter at the end of the filter
>> graph" },
>>>>>>>> /* audio options */
>>>>>>>> { "aframes", OPT_AUDIO | HAS_ARG | OPT_PERFILE |
>>>>>> OPT_OUTPUT,
>>>>>>>> { .func_arg = opt_audio_frames },
>>>>>>>> --
>>>>>>>> 2.7.4
>>>>>> What happens if user disables autoscale and the frame sizes do vary
>> but
>>>>>> the encoder doesn't support changing props?
>>>>> That's the point. Currently they would fail without specific notifications
>> for
>>>> this usage.
>>>>> One of the solutions is to declare
>>>> AV_CODEC_CAP_VARIABLE_DIMENSIONS capability for encoders [1],
>>>>> and prompt an error information [2] to indicate " Dynamic resolution
>>>> encode is not supported by this encoder."
>>>>> The further work would be providing dynamic encoding support for
>> some
>>>> encoders [3].
>>>>> So this patch is the first step.
>>>> Is this patch intended to be applied first, before the codec flag is
>>>> added and checked?
>>> Considering it won't impact the default behavior, IMHO yes it could be.
>> So, my question still stands. If it is applied tomorrow, and a user
>> disables autoscale, and ends up feeding frames of varying sizes to, say,
>> x264 or aom, what happens?
>>
> Failed without specific notifications for wrongly disabling autoscale.
>
> Taking x264 as an example to transcode clips with resolution changing
> from 352x288 to 240x196:
>
> [libx264 @ 0x5559143d51c0] Input picture width (352) is greater than stride (256)
> Video encoding failed
> (This differs according to the encoder.)
>
> BTW, it would be great if the patch set for codec flag and check could be applied at
> the same time.
The flag should be added first, then this patch updated to check and
abort if encoder doesn't have the capability.
Gyan
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