[FFmpeg-user] Merging VP9 files, without audio

[Dennis Mungai]

Hello there,

I'll answer the second part, concerning GPU acceleration:

First, consider what platform you're on. With Windows, you have access to
QuickSync (Intel), NVENC (Nvidia Kepler+) and AMD's VCE through AMF (On AMD
GCN-class hardware).
On Linux, you have access to VAAPI (on Intel and to a limited extent, AMD
GCN GPUs  with the mesa driver), QuickSync (Intel) and NVENC (Nvidia
Kepler+).
For applicable limitations, see this:
https://trac.ffmpeg.org/wiki/HWAccelIntro

A few rules of thumb:

1. If you're targeting VP8 and VP9 encoding on hardware, only Intel -based
IGPs expose this capability through VAAPI (at the moment). This is
available on Coffeelake and beyond.
2. Newer GPU generations across all vendors (AMD, Intel and NVIDIA) do
expose better support for the common codec types, namely VP8, VP9, HEVC and
of course, H.264/AVC (whose support at this point is ubiquitous).
However, this is not always the case. For instance, with AMD Polaris+,
their GPUs gained a HEVC encoder, and in return, dropped support for
B-frames in H.264/AVC encoding. Be on the look-out for such regressions.
3. Understand that hwaccels have limits, particularly with quality control
and format support, and as such, your mileage will vary. Carefully consider
the trade-offs vs any potential performance gains your workflow may gain.

Concerning performance:

1. The GT 1030 does not expose support for NVENC, so you can forget about
hardware-accelerated encoding on it. However, hardware accelerated decoding
should still be available for common formats.

2. For AMD GPUs and feature support, please start here:

(a). The AMF encoder limits wiki:
https://github.com/obsproject/obs-amd-encoder/wiki/Hardware-Support

(b). The Radeon feature matrix: https://www.x.org/wiki/RadeonFeature/

Do reach out if you have any further queries.

Warm regards,

Dennis.

On Thu, 29 Nov 2018 at 00:13, Morten W. Petersen <morphex at gmail.com> wrote:

> Hi again.
>
> From what I've seen, decoding and merging the files seems like the option
> available in ffmpeg.
>
> I read a bit on the ffmpeg concat (Concatenate in the wiki) page, but this
> is a bit over my head, I'm not that experienced with ffmpeg.
>
> I could also do motion detection on the fly in OpenCV, decoding and feeding
> video files to OpenCV, if that's supported.
>
> But I guess another question in all of this, is GPU-accelerated decoding
> and encoding. What brands of cards are supported for this? And what is the
> speed of a GT 1030 or R9 280X, compared to a modern CPU?
>
> Regards,
>
> Morten
>
> Den lør. 24. nov. 2018, 15.55 skrev Morten W. Petersen <morphex at gmail.com:
>
> > Hi there.
> >
> > I have a project which takes images using a webcam, called surveil:
> >
> > https://github.com/morphex/surveil
> >
> > These images are compiled into a (short) video, and then mailed.
> >
> > Now I'd like to add a feature, where videos are downloaded, and scanned
> > for motion.
> >
> > So these videos have to be merged together into one file, and I guess
> > prepending and appending 5 minutes to a 24 hour segment, should give for
> > example OpenCV the necessary data to detect motion in that segment.
> >
> > What's a good, non-resource-intensive way of merging VP9 videos into one,
> > using ffmpeg?
> >
> > Regards,
> >
> > Morten
> >
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