Im using ffmpeg-python to do some video transformations.
If I have the following:
infiles = []
infile = ffmpeg.input("/tmp/xxx.mp4")
infiles.append(
infile['v']
.filter('scale', size='1920x1080', force_original_aspect_ratio='decrease')
.filter('pad', '1920', '1080', '(ow-iw)/2', '(oh-ih)/2')
)
infiles.append(infile['a'])
(
ffmpeg
.concat(
*infiles, v=1, a=1, unsafe=True)
.output(out_tmp_file)
.run()
)
When I run it, I get the following error:
Stream specifier ':a' in filtergraph description [0:v]scale=force_original_aspect_ratio=decrease:size=1920x1080[s0];[s0]pad=1920:1080:(ow-iw)/2:(oh-ih)/2[s1];[s1][0:a]concat=a=1:n=1:unsafe=True:v=1[s2] matches no streams.
The above works if the video has audio