[FFmpeg-user] Tips on compressing videos created by GoPro

[Andrey Goreev]

Kieran,

Thank you for your comments.
I pasted my answers below yours.

Best regards,
Andrey

On Thu, Oct 19, 2017 at 8:26 AM, Kieran O Leary <kieran.o.leary at gmail.com>
wrote:

> Hi,
>
> On Thu, Oct 19, 2017 at 2:33 PM, Andrey Goreev <aegoreev at gmail.com> wrote:
>
> >
> > ffmpeg -i [INPUT-FILE]  -y -f mp4 -c:a libfdk_aac -b:a 192k -c:v libx264
> > -crf 23 -preset slow -map_metadata 0 [OUTPUT-FILE]
> >
>
> On a side note: I think the internal ffmpeg aac encoder might as good
> if not better now than libfsk_aac, so you should be able to just use
> -c:a aac instead. BUT is there a reason why you are increasing the
> bitrate from 128kb/sec to 192kb/sec? You're just making the file
> bigger. Why not just copy that stream instead with -c:a copy.
>

I don't recall why I picked libfdk_aac but I think there might have been
some issues with aac on some Linux distributions.
As for the bitrate and -c:a copy, thanks for pointing this. I will double
check what audio streams do files created by another devices in my
household have (samsung galaxy, phones and Pentax DSLR) and might adjust my
script.


> > FFprobe:
> > "Unsupported codec with id 0 for input stream 2"
> >
>
> This looks like it's referring to your timecode track - do you really
> want this? It looks like ffmpeg is ignoring it anyhow and not
> including it in your output. It is storing the initial timecode value
> as metadata though.
>

I do not worry about the timecode track so I would just ignore this.



> > FFmpeg:
> > "No pixel format specified, yuvj420p for H.264 encoding chosen.
> > Use -pix_fmt yuv420p for compatibility with outdated media players.  "
> >
>
> This is a seperate issue. It's most likely relating to your camera
> using the full range of 8-bit values (0-254) rather than the broadcast
> range (16-235). DSLR cameras are like this as well. You may find that
> your files are more compatible by heeding the warning and choosing
> -pix_fmt yuv420p, but you might experience some clipping, I am not
> sure actually. If you can play back the files on whatever device you
> wish to use, then I'd say ignore this warning for now, but keep it in
> mind if your files are unsupported in some media player.
>

I guess I will have do some tests on different devices and players and make
a decision.
My goal is to be able to watch the videos 20+ years down the road as that
is my family archive.