[FFmpeg-user] Ffmpeg fails to convert webm files when h264_nvenc forced

[Moritz Barsnick]

On Wed, Feb 28, 2018 at 05:53:17 +0000, oktay eşgül wrote:
> Here is the main steps of my process:
> 1.Split video and audio of the caller.
> time ffmpeg -y -i 230087_caller.webm -vn -ab 256 230087_caller.wav
> 2.Split video and audio of the callee
> time ffmpeg -y -i 230087_callee.webm -vn -ab 256 230087_callee.wav
> 3.Mux original caller video with callee audio to store the conversation.
> time ffmpeg -y -i 230087_caller.webm -i 230087_callee.wav -filter_complex '[0:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.5[a1];  [1:a]aformat=sample_fmts=fltp:sample_rates=44100:channel_layouts=stereo,volume=0.5[a2]; [a1][a2]amerge,pan=stereo|c0<c0+c2|c1<c1+c3[out]' -map 0:v -map '[out]' -c:v copy -c:a libvorbis -shortest -f webm caller_temp.webm
> 4.Add time fontfile to the caller_temp fil which fails with below error.
> time ffmpeg -y -i caller_temp.webm -vf drawtext=fontfile=/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf:x=8:y=8:fontsize=16:fontcolor=yellow at 1:expansion=strftime:basetime=1518172680000000:text='%Y-%m-%d %H-%M-%S' -strict -2 -shortest -c:a libvorbis -c:v h264_nvenc final_font_test.webm

I'm pretty sure this can all be done in one step, but that was not the
aim of your email. ;-)

> [webm @ 0x29e8540] Only VP8 or VP9 video and Vorbis or Opus audio and
> WebVTT subtitles are supported for WebM.
[...]
> However,when I have changed the output file format to mp4/avi/mpeg GPU can
> be used without any issue.Yet ,webm is important for us as the other
> container file size becomes risky with storage perspective of view.

Did you read this message? ffmpeg's webm muxer refuses to mux H.264
video into WebM. You need to encode to vp9 or vp9. (I realize that
there's no nvenc acceleration for that though, IIUC.)

Moritz