ffmpeg conversion for Chromecast

On an old Google Chromecast 1, I've found the following to produce playable content:

ffmpeg4 -i input.mp4 -preset fast -c:a aac -b:a 192k -ac 2 -c:v libx264 -b:v 1024k -profile:v high -level 4.1 -crf -1 -pix_fmt yuv420p output.mp4

More complex transcoding is possible. Eg. With an input where the video is fine, but the audio stream is aac 5.1 and refuses to play, we can copy the video stream, and map the audio stream twice, keeping the aac 5.1 stream and adding a second 192kb/s aac stereo stream. Eg.

ffmpeg4 -i input.mp4 -map 0:v:0 -c:v copy -map 0:a:0 -map 0:a:0 -c:a:0 aac -ac:a:0 2 -b:a:0 192k -c:a:1 copy output.mp4

From DVD files

Using the 3rd audio track (which are numbered from zero).

ffmpeg4 -i "concat:$(perl -e 'print join("|", @ARGV);' VTS_01_[1-9].VOB)" -map 0:v:0 -map 0:a:2 -preset fast -c:a aac -b:a 192k -ac 2 -c:v libx264 -b:v 1024k -profile:v high -level 4.1 -crf -1 -pix_fmt yuv420p output.mp4

Notes

• aac 5.1 audio doesn't seem to work.
• use -t <duration_secs> to test settings on a small portion of the file.
• -crf -1 specifies constant quality mode, and is roughly equivalent to -crf 30. For higher quality, try, eg. -crf 25.
• use eg. -s 1920x1080 to scale.
• the mp4 container supports mov_text subtitle encoding, but it's not supported by Chromecast.
• mkv container supports webvtt subtitle encoding, which is supported by Chromecast.

See also

• Supported Media for Google Cast.