[FFmpeg-user] Trying to create matching multi-audio-track mp4s from ProRes sources

[Gyan]

On 13-02-2019 10:32 PM, Harvey Pikelberger wrote:
> I've got a bunch of 4- and 5-audio-track ProRes sources.
> I want to create h.264/mp4 proxies of each, matching the source audio assigns
> The FFmpeg code I'm using is tripping up over time code and codec issues.
>
> Here's the code:
> -i '/Path/To/ProRes/Source.mov' -map 0 -g 48 -c:v libx264 -profile:v baseline -crf 16 -c:a aac -b:a 256k -vf scale=1280:720 -pix_fmt yuv420p '/Path/To/Mp4/Dest.mp4'
>
> As I understand -map 0 is what conforms the audio assigns.
> Not sure what -g 48 is doing, but removing still gets errors.
>
> Here are the errors:
> [mp4 @ 0x7fe633006000] You requested a copy of the original timecode track so timecode metadata are now ignored
> [mp4 @ 0x7fe633006000] Could not find tag for codec none in stream #2, codec not currently supported in container
> Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
> Error initializing output stream 0:1 --
> [aac @ 0x7fe633801e00] Qavg: nan
> Conversion failed!
>

`-map 0` maps all streams for output including those that the output may 
not be able to handle, like the single-packet timecode stream. However, 
ffmpeg will copy it using the metadata entry created when reading the input.

So, unmap the data streams,

     -i '/Path/To/ProRes/Source.mov' -map 0 0 -map -0:d -g 48 -c:v 
libx264 -profile:v baseline -crf 16 -c:a aac -b:a 256k -vf 
scale=1280:720 -pix_fmt yuv420p '/Path/To/Mp4/Dest.mp4'

Gyan