On 2/15/20, Fu, Linjie <linjie...@intel.com> wrote:
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of
>> Nicolas George
>> Sent: Saturday, February 15, 2020 19:01
>> To: FFmpeg development discussions and patches <ffmpeg-
>> de...@ffmpeg.org>
>> Cc: Fu, Linjie <linjie...@intel.com>; Eoff, Ullysses A
>> <ullysses.a.e...@intel.com>
>> Subject: Re: [FFmpeg-devel] [PATCH] fftools/ffmpeg_filter: add -autoscale
>> to disable/enable the default scale
>>
>> Linjie Fu (12020-02-15):
>> > 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.e...@intel.com>
>> > Signed-off-by: Linjie Fu <linjie...@intel.com>
>> > ---
>> >
>> > Using autoscale as an output option and fix the missing spaces.
>> >
>> > doc/ffmpeg.texi | 16 ++++++++++++----
>> > fftools/ffmpeg.h | 3 +++
>> > fftools/ffmpeg_filter.c | 2 +-
>> > fftools/ffmpeg_opt.c | 8 ++++++++
>> > 4 files changed, 24 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.
>> > -
>> > -@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}.
>> > +
>> > +@item -autorotate
>> > +Automatically rotate the video according to file metadata. Enabled by
>> > +default, use @option{-noautorotate} to disable it.
>> > +
>> > +@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..62bcfc1 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 +3652,12 @@ 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_OUTPUT,
>> > { .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."},
>>
>> The help text for most options is half a line. This one is four long
>> lines. Maybe this is misusing the field: a short summary here, the full
>> explanation in the doc.
>
> How about shortening into
> "automatically insert a scale filter at the end of the filter graph if a
> resolution change is detected (enabled by default)."
> in the help message and keep the current explanation unchanged in doc?
last part in () is redundant.
>
>> Regards,
>>
>> --
>> Nicolas George
>
> Thanks for pointing this out.
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