[FFmpeg-devel] [RFC PATCH] ffmpeg_videotoolbox: skip memory copy if hwaccel_output_format match

Zhao Zhili quinkblack at foxmail.com
Tue Apr 27 08:09:56 EEST 2021

From: zhilizhao <zhilizhao at tencent.com>

Simple test results:

./ffmpeg -y -hwaccel videotoolbox -hwaccel_output_format videotoolbox_vld \
  -i test.mp4 -an -c:v h264_videotoolbox -benchmark out.mp4

frame= 1221 fps= 66 q=-0.0 Lsize=    3144kB time=00:00:20.33 bitrate=1266.6kbits/s dup=4 drop=0 speed= 1.1x
bench: utime=2.714s stime=1.218s rtime=18.574s

frame= 1221 fps=137 q=-0.0 Lsize=    3144kB time=00:00:20.33 bitrate=1266.4kbits/s dup=4 drop=0 speed=2.28x
bench: utime=1.450s stime=1.440s rtime=8.924s

It has limited usecase since there is no video filter support, so
a log message is added to notify the user.
It has a good performance with limited usecases like transcoding without
autoscale/autorotate, and I don't know if it break some special usecase,
since the RFC.

 fftools/ffmpeg_videotoolbox.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fftools/ffmpeg_videotoolbox.c b/fftools/ffmpeg_videotoolbox.c
index a6b78d0f7d..4ba8618539 100644
--- a/fftools/ffmpeg_videotoolbox.c
+++ b/fftools/ffmpeg_videotoolbox.c
@@ -29,6 +29,7 @@
 typedef struct VTContext {
     AVFrame *tmp_frame;
+    int log_once;
 } VTContext;
 char *videotoolbox_pixfmt;
@@ -44,6 +45,13 @@ static int videotoolbox_retrieve_data(AVCodecContext *s, AVFrame *frame)
     int linesize[4] = { 0 };
     int planes, ret, i;
+    if (frame->format == ist->hwaccel_output_format) {
+        av_log_once(s, AV_LOG_INFO, AV_LOG_TRACE, &vt->log_once,
+            "There is no video filter for videotoolbox pix_fmt now, remove the "
+            "-hwaccel_output_format option if video filter doesn't work\n");
+        return 0;
+    }
     switch (pixel_format) {

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