Fix h264_v4l2m2m acceleration in Raspberry Pi 4

[MELSunny]

Changes

Fixed by replacing pixel format from NV21 to yuv420p.

Issues

Error when enabling v4l acceleration in Raspberry Pi 4
Logs:
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file:/srv/dev-disk-by-uuid-17558f66-a74f-4416-b283-4c70bb44b6f8/MediaLibrary/Movie/test.mp4':
Metadata:
major_brand : isom
minor_version : 1
compatible_brands: isomavc1
creation_time : 2015-04-23T22:01:41.000000Z
Duration: 02:08:29.76, start: 0.000000, bitrate: 2173 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/bt709/unknown), 1920x800 [SAR 1:1 DAR 12:5], 2075 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)
Metadata:
creation_time : 2015-04-23T22:01:41.000000Z
handler_name : video.264#trackID=1:fps=23.976 - Imported with GPAC 0.5.0-rev
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)
Metadata:
creation_time : 2015-04-23T22:01:53.000000Z
handler_name : GPAC ISO Audio Handler
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (h264_v4l2m2m))
Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[h264_v4l2m2m @ 0x559ce26380] Using device /dev/video11
[h264_v4l2m2m @ 0x559ce26380] driver 'bcm2835-codec' on card 'bcm2835-codec-encode' in mplane mode
[h264_v4l2m2m @ 0x559ce26380] requesting formats: output=YU12 capture=H264
[h264_v4l2m2m @ 0x559ce26380] Encoder requires yuv420p pixel format.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!

[MELSunny]

Related discussing jellyfin/jellyfin-ffmpeg#310

[nyanmisaka]

Can you remove this field and add a new case for V4L2 encoder after these lines?

jellyfin/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

Lines 2722 to 2725 in 939d96e

	if (isVaapiEncoder)
	{
	outFormat = "nv12";
	}

[Maxplosion]

typo? nv12 / nv21

[aolszowka]

@nyanmisaka I submitted a new PR (#7291) that moves this change down to that location, however I did not fix the potential issue that @Maxplosion pointed out? All credit to @MELSunny as this is more or less just an update on his PR

[MELSunny]

Thank you very much for your PR @aolszowka.
nv12 is tested to work on raspberry pi 4 as well.
@Maxplosion nv21 is not a typo, it exists in pixel format in FFmpeg. But nv21 is not supported by raspberry pi encoder h264_v4l2m2m.

[MELSunny]

Can you remove this field and add a new case for V4L2 encoder after these lines?

jellyfin/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

Lines 2722 to 2725 in 939d96e

	if (isVaapiEncoder)
	{
	outFormat = "nv12";
	}

Many thanks for the contribution by @aolszowka,
I have updated the code according to @nyanmisaka advice

deae9bb

[emgre]

Does someone know why this particular pixel format was explicitly specified for h264_v4l2m2m? Was it because of a particular hardware? My guess would be that it's related to some Android device. What if we let ffmpeg choose the pixel format?

[aolszowka]

@emgre As per the PR the hardware being targeted here is a Raspberry Pi 4 (https://www.raspberrypi.com/products/raspberry-pi-4-model-b/specifications/ a Broadcom BCM2711 SOC). I suspect that that pixel format is being specifically targeted due to ffmpeg stating the following (from the log above):

[h264_v4l2m2m @ 0x559ce26380] Encoder requires yuv420p pixel format.

[emgre]

@aolszowka I understand the current change, my question was why nv21 was explicitely set originally?

[aolszowka]

@emgre Ah that is a different question, I suspect as you do that this was for support for an Android Device, as the original drop down for this used to read Exynos V4L2M2. The Exynos is a SoC similar to the Broadcom on the Pi, but on different boards, most likely a ODROID of some type. A search of the previous issues shows at least one user reporting an issue with it.

At some point this text was modified to no loner reference this specific SoC (I am unable to find the PR/Commit this was done on) the original changes look to be done on #1369?

[nyanmisaka]

Closed in #7291