When switching from libx264 to h264_v4l2m2m encoder in FFmpeg for YouTube streaming, the output video's aspect ratio changes from 16:9 to 1:1 with black bars on the sides, despite keeping the same resolution settings.
Original working command (with libx264):
ffmpeg -f v4l2 \
-input_format yuyv422 \
-video_size 1280x720 \
-framerate 30 \
-i /dev/video0 \
-f lavfi \
-i anullsrc=r=44100:cl=stereo \
-c:v libx264 \
-preset ultrafast \
-tune zerolatency \
-b:v 2500k \
-c:a aac \
-b:a 128k \
-ar 44100 \
-f flv rtmp://a.rtmp.youtube.com/live2/[STREAM-KEY]
When I replaced libx264 with h264_v4lm2m, it always produce a square resolution, and it automatically adds black bars to the top and the bottom of the sides of the camera. I currently using a Rasberry Pi 4 model B, with a webcam that I believe supports the 16:9 ratio (I've verified using v4l2-ctl --list-formats-ext -d /dev/video0 command)
I've tried the follows:
- Adding
-aspect 16:9parameter in the ffmpeg command - Adding video filters such as
-vf "scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1"None of these give me the correct aspect ratio.
How can I make the h264_v4l2m2m encoder maintain the original 16:9 aspect ratio without adding black bars? Is this a known limitation of the encoder, or am I missing some required parameters?
