LibVLC and avcodec-hw

[dharks]

I'm working on a video player app to play H.264 video, using LibVLC 2.1.4 on Linux. The hardware this app will run on is an AMD APU without enough horsepower to do the decoding in CPU -- however, libva-based decode works like a champ.

According to the wiki entry on VLC_GPU_Decoding, "By default, hardware acceleration is disabled (and consequently, hardware acceleration is not yet available to external application via LibVLC)."

Is this still the case? Is there any way to turn on libva decode in a LibVLC app? Passing "--avcodec-hw=any" or "--avcodec-hw=vaapi" to the libvlc instance does not seem to convince the system to turn it on.

Thanks much!

[Rémi Denis-Courmont]

LibVLC 2.2.0+ will enable VDPAU automatically where available. VA support is not complete enough to be enabled in LibVLC.

[mgcrea]

I've just updated VLC and I am encountering this as well (on a modern NUC BayTrail based machine running Ubuntu 14.04).

In the V2.1 branch, libvlc did defaulted to VAAPI for hardware decoding, and everything was working great.
But since v2.2, it tries to use VDPAU and fails. I'm using latest oibaf intel drivers. I get :

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"Failed to open VDPAU backend libvdpau_i965.so: cannot open shared object file: No such file or directory"

I've seen that the workaround suggested is to use:

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VDPAU_DRIVER=va_gl cvlc media.mp4

But it fails on the first frame:

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[00007f2674c30b78] avcodec decoder: Using OpenGL/VAAPI/libswscale backend for VDPAU for hardware decoding. WARNING: Unsupported the FMO/ASO constraints!!! [00007f2648001268] vdpau_display vout display error: video mixer surface width capabilities query failure: VDP_STATUS_NO_IMPLEMENTATION

However it works flawlessly with :

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cvlc media.mp4 --avcodec-hw=vaapi

I get (same as with v2.1):

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[00007f1f3cc30b78] avcodec decoder: Using Intel i965 driver for Intel(R) Bay Trail - 1.4.1 for hardware decoding. libva info: VA-API version 0.36.0

My issue is that I'm relying on libVLC and I can't find a way to force libVLC to preserve the v2.1 behavior (it did default to VAAPI!). And reading from you, it looks like this is not possible at all.

Is there anything new on this subject? Since it's a breaking change for me (and probably lot of libVLC implementations that were working fine defaulting to VAAPI), is there a way this might get fixed in the future?

Thanks!

[Rémi Denis-Courmont]

In the V2.1 branch, libvlc did defaulted to VAAPI for hardware decoding, and everything was working great.

This is not true. In V2.1, libvlc did not use hardware acceleration for decoding at all (SIMD aside) by default.

But since v2.2, it tries to use VDPAU and fails.

That is expected if you have Intel HD Graphics, and the result will be the same as in V2.1, except for the short time spent attempting to load the driver and printing error message.

I've seen that the workaround suggested is to use:

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VDPAU_DRIVER=va_gl cvlc media.mp4

You can do that but that is not recommended unless you are sure that your version of VA-GL is robust enough.

[mgcrea]

This is not true. In V2.1, libvlc did not use hardware acceleration for decoding at all (SIMD aside) by default.

Very strange. I have dozens of linux players that show the same behavior, VA-API is loaded and working. libvlc is being piloted by https://github.com/tjfontaine/node-vlc (using ffi).

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VLC media player 2.1.6 Rincewind (revision 2.1.4+git20141006+r54582+19+11~ubuntu14.04.1)

Sample NodeJS output:

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2014-11-25T14:58:23.873Z - debug: vlc - VLCPlayer.play /srv/player/data/media/547495f1-1574-483f-ba91-06e35e1706d2/media/Elysium_trailer_1-4K-HDTN.mp4 libva info: VA-API version 0.36.0 libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so libva info: Found init function __vaDriverInit_0_36 libva info: va_openDriver() returns 0 [0x7f47c0c6b418] avcodec decoder: Using VA API version 0.36 for hardware decoding. [h264 @ 0x7f47c0c6c020] Cannot parallelize deblocking type 1, decoding such frames in sequential order Fontconfig warning: FcPattern object size does not accept value "0" Fontconfig warning: FcPattern object size does not accept value "0"

[Rémi Denis-Courmont]

If you have patched libvlc or are using non-default settings, you can do that just as well with V2.2, but you are on your own.

[mgcrea]

I'm not using any patched libvlc. I just installed with apt-get from https://launchpad.net/~videolan/+archiv ... able-daily

Settings passed to libvlc 2.1.0:

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"--ignore-config", "--no-disable-screensaver", "--intf=dummy", "--album-art=0", "--no-media-library", "--no-osd", "--no-stats", "--no-video-title-show", "--avcodec-hw=any"

So it looks like "avcodec-hw=any" option has a new behavior with libVLC v2.2.
Since "--avcodec-hw=vaapi" is not working on v2.2.0, I can't reuse the same settings with 2.2.0 and it's a breaking change for me or any developer using "avcodec-hw=any".

Thanks.

[Rémi Denis-Courmont]

Parameters to libvlc_new() are not portable across versions. No news here:
https://www.videolan.org/developers/vlc ... ba6e2f7764

[mgcrea]

Thanks for your help, lesson learnt .