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 -i input.mp4 out1.yuv -noautoscale out2.yuv -autoscale 0 out3.yuv

Update docs.

Suggested-by:  Mark Thompson <sw@jkqxz.net>
Reviewed-by:   Nicolas George <george@nsup.org>
Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>
Signed-off-by: Linjie Fu <linjie.fu@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 828cb2a4ff..6e3f2545c7 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -229,6 +229,8 @@ 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;