[Libav-user] Raspberry pi 4 encoding h264_v4l2m2m (Weylus): no picture and warnings

Paul nannapie at hotmail.co.uk
Sat Feb 26 19:55:57 EET 2022 

Erm I’ve had issues with jpeg encodings in the past. I don’t know if h264 suffers from this but the max resolution you can send is around 1920 by 1080 (it’s in the http spec). Dunno if this helps but it might be worth just double checking that you are not falling foul of that. 

You might not be if the stuff is arriving. 

All my best,

Paul 

Sent from the top a castle using a moderately sized European swallow 

> On 26 Feb 2022, at 15:38, Alexander Kamm <akamm at web.de> wrote:
> 
> Thank you for your time an effort in developing libav...
> 
> I want to use libav and ffmpeg together with weylus
> (https://github.com/H-M-H/Weylus) on the raspberry pi 4. If I use
> libx264 software encoding everything is working except that the
> performance is to low for an adequate fps in encoding the screen on the
> raspberry pi.
> 
> Together with the developer of weylus I'm trying to get the hardware
> encoding with h264_v4l2m2m working. Actually the video stream can't be
> decoded on the client side and I have some warnings and error in the log
> file on the raspberry pi (see below).
> 
> Expected behavior
> 
> Screen gets encoded on the rasperry pi with h264_4vl2m2m and decoded in
> the browser on the client side.
> 
> Actual behavior
> 
> Encoding with h262_4vl2m2m delivers a video stream (?) but it can't be
> decoded in Firefox or Chromium -> no picture. Other features of weylus
> are working as expected (controlling the pi form within the client browser).
> 
> What I tried:
> 
> To get "repeat parameter sets = 1" working: Patched (see below)
> libavcodec / h264_4vl2m2m and build it with the raspbian source package.
> 
> different values for gop size and timebase
> 
> Actually I have no clue which is the root of the problem. Is it
> something that is mentioned in the log or do I miss something else
> completely?
> 
> Any support is appreciated!
> 
> ______________________________________________________________________________________________
> 
> Log file (partly)
> 
> 2022-02-23T10:10:27.189023Z  INFO weylus::log: Using device /dev/video11
> 2022-02-23T10:10:27.189434Z  INFO weylus::log: driver 'bcm2835-codec' on
> card 'bcm2835-codec-encode' in mplane mode
> 2022-02-23T10:10:27.189579Z  INFO weylus::log: requesting formats:
> output=YU12 capture=H264
> 2022-02-23T10:10:27.215520Z TRACE weylus::log: output: YU12 16 buffers
> initialized: 1124x0632, sizeimage 01092096, bytesperline 00001152
> 2022-02-23T10:10:27.221552Z TRACE weylus::log: capture: H264 04 buffers
> initialized: 1124x0632, sizeimage 00552960, bytesperline 00000000
> 2022-02-23T10:10:27.221896Z TRACE weylus::log: Failed to set number of
> B-frames: Invalid argument
> 2022-02-23T10:10:27.222071Z TRACE weylus::log: Failed to get number of
> B-frames
> 2022-02-23T10:10:27.222268Z  WARN weylus::log: Failed to set timeperframe
> 2022-02-23T10:10:27.222592Z TRACE weylus::log: Encoder: header mode = 0
> 2022-02-23T10:10:27.222874Z TRACE weylus::log: Encoder: bit rate = 200000
> 2022-02-23T10:10:27.223056Z TRACE weylus::log: Failed to set frame level
> rate control: Invalid argument
> 2022-02-23T10:10:27.223221Z  WARN weylus::log: Failed to set gop size:
> Invalid argument
> 2022-02-23T10:10:27.223488Z TRACE weylus::log: Encoder: repeat parameter
> sets = 1
> 2022-02-23T10:10:27.223644Z TRACE weylus::log: Encoder Context: id (27),
> profile (-99), frame rate(0/1), number b-frames (0), gop size (12), bit
> rate (200000), qmin (-1), qmax (-1)
> 2022-02-23T10:10:27.223929Z TRACE weylus::log: Encoder: minimum video
> quantizer scale = 0
> 2022-02-23T10:10:27.224410Z TRACE weylus::log: Encoder: maximum video
> quantizer scale = 51
> 2022-02-23T10:10:27.225093Z DEBUG weylus::log: Empty MOOV enabled;
> disabling automatic bitstream filtering
> 2022-02-23T10:10:27.225614Z DEBUG weylus::log: Not writing 'clli' atom.
> No content light level info.
> 2022-02-23T10:10:27.225836Z DEBUG weylus::log: Not writing 'mdcv' atom.
> Missing mastering metadata.
> 2022-02-23T10:10:27.229606Z  INFO weylus::log: Video:
> 1124x632 at h264_v4l2m2m pix_fmt: yuv420p
> 2022-02-23T10:10:32.344507Z ERROR weylus::log: Application provided
> invalid, non monotonically increasing dts to muxer in stream 0: 448560 >= 0
> 2022-02-23T10:10:37.245047Z ERROR weylus::log: Application provided
> invalid, non monotonically increasing dts to muxer in stream 0: 889650 >= 0
> 2022-02-23T10:10:42.185585Z ERROR weylus::log: Application provided
> invalid, non monotonically increasing dts to muxer in stream 0: 1335330 >= 0
> 2022-02-23T10:10:47.063446Z ERROR weylus::log: Application provided
> invalid, non monotonically increasing dts to muxer in stream 0: 1774890 >= 0
> 2022-02-23T10:10:51.928700Z ERROR weylus::log: Application provided
> invalid, non monotonically increasing dts to muxer in stream 0: 2212740 >= 0
> 
> ...
> 
> _________________________________________________________________________--
> 
> Hard- / Software
> 
> Server system:
> 
> Raspberry pi 4, 4Gb
> 
> Raspbian 64 bit
> 
> ffmpeg 4.3.3
> 
> Client system
> 
> Surface 5
> 
> Linux Mint 20.04
> 
> Firefox 97.1 (64 bit)
> 
> Chromium 98.0.4758.102 (Offizieller Build) for Linux Mint (64-Bit)
> 
> ____________________________________________________________________________
> 
> Patch:
> 
> diff --git a/libavcodec/v4l2_m2m_enc.c b/libavcodec/v4l2_m2m_enc.c
> index f644b50133..4b2ca7bdf4 100644
> --- a/libavcodec/
> +++ b/libavcodec/v4l2_m2m_enc.c
> @@ -197,6 +197,7 @@ static int v4l2_prepare_encoder(V4L2m2mContext *s)
>      v4l2_set_ext_ctrl(s, MPEG_CID(BITRATE) , avctx->bit_rate, "bit
> rate", 1);
>      v4l2_set_ext_ctrl(s, MPEG_CID(FRAME_RC_ENABLE), 1, "frame level
> rate control", 0);
>      v4l2_set_ext_ctrl(s, MPEG_CID(GOP_SIZE), avctx->gop_size,"gop
> size", 1);
> +    v4l2_set_ext_ctrl(s, MPEG_CID(REPEAT_SEQ_HEADER), 1,"repeat
> parameter sets", 1);
> 
>      av_log(avctx, AV_LOG_DEBUG,
>          "Encoder Context: id (%d), profile (%d), frame rate(%d/%d),
> number b-frames (%d), "
> 
> 
> 
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