[FFmpeg-devel] [PATCH 1/2] fftools/ffmpeg_filter: add -autoscale to disable/enable the default scale

[Michael Niedermayer]

On Mon, Jul 15, 2019 at 06:38:35PM +0800, Linjie Fu wrote:
> 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 to indicate whether auto inserting the scale
> filter in the filter graph:
>     -noautoscale or -autoscale 0:
>         disable the default auto scale filter inserting.
> 
> Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> ---
>  fftools/ffmpeg.c        | 1 +
>  fftools/ffmpeg.h        | 4 ++++
>  fftools/ffmpeg_filter.c | 2 +-
>  fftools/ffmpeg_opt.c    | 5 +++++
>  4 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 01f04103cf..5d52430b1e 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -2133,6 +2133,7 @@ static int ifilter_send_frame(InputFilter *ifilter, AVFrame *frame)
>  
>      /* determine if the parameters for this input changed */
>      need_reinit = ifilter->format != frame->format;
> +    fg->autoscale = ifilter->ist->autoscale;
>  
>      switch (ifilter->ist->st->codecpar->codec_type) {
>      case AVMEDIA_TYPE_AUDIO:
> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> index 7b6f802082..1602406581 100644
> --- a/fftools/ffmpeg.h
> +++ b/fftools/ffmpeg.h
> @@ -133,6 +133,8 @@ typedef struct OptionsContext {
>      int        nb_hwaccel_output_formats;
>      SpecifierOpt *autorotate;
>      int        nb_autorotate;
> +    SpecifierOpt *autoscale;
> +    int        nb_autoscale;
>  
>      /* output options */
>      StreamMap *stream_maps;
> @@ -285,6 +287,7 @@ typedef struct FilterGraph {
>  
>      AVFilterGraph *graph;
>      int reconfiguration;
> +    int autoscale;
>  
>      InputFilter   **inputs;
>      int          nb_inputs;
> @@ -335,6 +338,7 @@ typedef struct InputStream {
>      int guess_layout_max;
>  
>      int autorotate;
> +    int autoscale;
>  
>      int fix_sub_duration;
>      struct { /* previous decoded subtitle and related variables */
> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
> index 72838de1e2..2a2eb080eb 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) && fg->autoscale) {
>          char args[255];
>          AVFilterContext *filter;
>          AVDictionaryEntry *e = NULL;
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index f5ca18aa64..47f90c22aa 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -742,7 +742,9 @@ static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
>          MATCH_PER_STREAM_OPT(ts_scale, dbl, ist->ts_scale, ic, st);
>  
>          ist->autorotate = 1;
> +        ist->autoscale  = 1;
>          MATCH_PER_STREAM_OPT(autorotate, i, ist->autorotate, ic, st);
> +        MATCH_PER_STREAM_OPT(autoscale, i, ist->autoscale, ic, st);
>  
>          MATCH_PER_STREAM_OPT(codec_tags, str, codec_tag, ic, st);
>          if (codec_tag) 
{

> @@ -3640,6 +3642,9 @@ 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_INPUT,                                { .off = OFFSET(autoscale) },
> +        "automatically insert correct scale filters" },

I think this description is inadequate to understand what the option does.
Scale filters are inserted at various places (for example within a filter
graph). This option here affects a specific case.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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