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• Use ffmpeg multiple h264_nvenc instances will crash occurs during release

  13 août 2024, par yang zhao

  Use FFMpeg, When multiple threads use multiple h264_nvenc instances(one instance per thread), an exception crash occurs during release(avcodec_free_context), and the final exception occurs in libnvcuvid.so.
I don't know what the reason is ? Please help, thanks.
The same problem exists : ffmpeg v5.0.1 + cuda v11.6 and ffmpeg v7.0.1 + cuda v12.2
operating system：Ubuntu 22.04.4 LTS

  


  The specific code is as follows :

  


  class NvencEncoder {
public:
    NvencEncoder() {}
    ~NvencEncoder { Close(); }
    
    bool Open() {
        auto encoder = avcodec_find_encoder_by_name("h264_nvenc");
        pCodecCtx_ = avcodec_alloc_context3(encoder);
        if (!pCodecCtx_)
            return false;

        int width = 1920;
        int height = 1080;
        int bitrate = 1000000;
        
        pCodecCtx_->codec_type = AVMEDIA_TYPE_VIDEO;
        pCodecCtx_->pix_fmt = AV_PIX_FMT_YUV420P;
        pCodecCtx_->width = width;
        pCodecCtx_->height = height;
        pCodecCtx_->bit_rate = bitrate;
        pCodecCtx_->rc_min_rate = bitrate;
        pCodecCtx_->rc_max_rate = bitrate;
        pCodecCtx_->bit_rate_tolerance = bitrate;
        pCodecCtx_->rc_buffer_size = bitrate / 2;
        pCodecCtx_->time_base = AVRational{ 1, 90000 };
        pCodecCtx_->framerate = AVRational{ 25, 1 };
        pCodecCtx_->gop_size = 50;
        pCodecCtx_->max_b_frames = 0;
        pCodecCtx_->delay = 0;
        pCodecCtx_->refs = 2;
        pCodecCtx_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

        av_opt_set_int(pCodecCtx_->priv_data, "gpu", 0, 0);
        av_opt_set(pCodecCtx_->priv_data, "preset", "llhp", 0);
        av_opt_set(pCodecCtx_->priv_data, "rc", "cbr", 0);
        av_opt_set(pCodecCtx_->priv_data, "profile", "main", 0);
        av_opt_set(pCodecCtx_->priv_data, "zerolatency", "1", 0);
        av_opt_set(pCodecCtx_->priv_data, "delay", "0", 0);
        av_opt_set(pCodecCtx_->priv_data, "preset", "medium", 0);

        int ret = avcodec_open2(pCodecCtx_, encoder, nullptr);
        if (ret < 0)
            return false;

        pkt_ = av_packet_alloc();
        if (!pkt_)
            return false;

        char output_mp4[] = "output.mp4";
        ret = avformat_alloc_output_context2(&avMp4Context_, NULL, "mp4", output_mp4);
        if (ret < 0)
            return false;
            
        mp4_stream_ = avformat_new_stream(avMp4Context_, nullptr);
        if (!mp4_stream_)
            return false;

        ret = avcodec_parameters_copy(mp4_stream_->codecpar, out_stream_->codecpar);
        if (ret < 0)
            return false;
            
        mp4_stream_->codecpar->codec_tag = 0;

        if (!(avMp4Context_->oformat->flags & AVFMT_NOFILE)) {
            ret = avio_open(&avMp4Context_->pb, output_mp4_.c_str(), AVIO_FLAG_WRITE);
            if (ret < 0) {
                return false;
        }
        return true;
    }

    void Close() {
        if (pCodecCtx_)
            avcodec_free_context(&pCodecCtx_); // Crash will occur in libnvcuvid.so

        if (avMp4Context_) {
            if (avMp4Context_->oformat && !(avMp4Context_->oformat->flags & AVFMT_NOFILE)) {
                avio_closep(&avMp4Context_->pb);
            }
            avformat_free_context(avMp4Context_);
            avMp4Context_ = nullptr;
        }
        
        if (pkt_)
            av_packet_free(&pkt_);
    }

    bool InputFrame(AVFrame* frame) {
        int ret = avcodec_send_frame(pEncoderVideoCodecCtx_, frame);
        if (ret < 0)
            return false;
            
        while (ret >= 0) {
            ret = avcodec_receive_packet(pEncoderVideoCodecCtx_, pkt_);
            if (ret < 0)
                break;

            if (avNotHeadWrited_) {
                ret = avformat_write_header(avMp4Context_, &opts);
                if (ret < 0) {
                    av_packet_unref(pkt_);
                    break;
                }
                avNotHeadWrited_ = false;
            }

            av_packet_rescale_ts(pkt_, pCodecCtx_->time_base, mp4_stream_->time_base);
            ret = av_write_frame(avMp4Context_, pkt_);
            if (ret < 0) {
                av_packet_unref(pkt_);
                break;
            }

            av_packet_unref(pkt_);
        }
        
        return (ret >= 0);
    }
private:
    AVPacket* pkt_ = nullptr;
    AVCodecContext* pCodecCtx_ = nullptr;
    AVFormatContext* avMp4Context_ = nullptr;
    AVStream* mp4_stream_ = nullptr;
    avNotHeadWrited_ = true;
}

uint8_t* data = nullptr; //a frame of yuv420 data
void Run(int idx);

int main() {
    //Fill a frame of yuv420 data here
    ...

    std::thread th[3];
    for (int i = 0; i < 3; i++) {
        th[i] = std::thread(Run, i);
        sleep(3);
    }

    sleep(35);

    for (int i = 0; i < 3; i++) {
        if (th[i].joinable()) {
            printf("thread %d join()\n", i);
            th[i].join();
        }
    }

    free(data);
    printf("Exit\n");
}

void Run(int idx) {
    printf("Run() thread(%d)\n", idx);
    //cudaSetDevice(0);

    auto nvenc = new NvencEncoder(ffpar, FFOutputCB);
    if (!nvenc->Open()) {
        delete nvenc;
        return;
    }

    auto avframe_ = av_frame_alloc();
    avframe_->width = 1920;
    avframe_->height = 1080;
    avframe_->format = AV_PIX_FMT_YUV420P;

    int ret = av_frame_get_buffer(avframe_, 0);
    if (ret < 0) {
        printf("av_frame_get_buffer() is error %d\n", ret);
        delete nvenc;
        av_frame_free(&avframe_);
        return;
    }

    int frame_size = 1920 * 1080;
    double one_frame_us = 1000000.0 / 25.0;
    unsigned long frame_count = 0;
    struct timeval t1, t2;
    double timeuse;

    AVRational timebase = { ffpar.timebase_num, ffpar.timebase_den };
    std::int64_t llCalcDuration = (double)AV_TIME_BASE / 25.0;
    double in_stream_timebase = av_q2d(timebase);
    std::int64_t duration = (double)llCalcDuration / (double)(in_stream_timebase * AV_TIME_BASE);
    avframe_->time_base = timebase;
    gettimeofday(&t1, NULL);

    while (frame_count < 25*30) { //30 seconds

        avframe_->pts = (double)(frame_count * llCalcDuration) / (double(in_stream_timebase * AV_TIME_BASE));
        //avframe_->duration = duration;
        frame_count++;

        ret = av_frame_make_writable(avframe_);
        if (ret < 0) {
            printf("av_frame_make_writable() is error %d\n", ret);
            break;
        }

        // copy YUV420
        memcpy(avframe_->data[0], data, frame_size);
        memcpy(avframe_->data[1], data + frame_size, frame_size / 4);
        memcpy(avframe_->data[2], data + frame_size * 5 / 4, frame_size / 4);

        ret = nvenc->InputFrame(avframe_);
        if (ret < 0) {
            printf("InputFrame() is error: %d\n", ret);
            break;
        }

        // frame rate
        gettimeofday(&t2, NULL);
        timeuse = (t2.tv_sec - t1.tv_sec) * 1000000 + (t2.tv_usec - t1.tv_usec); //us
        if (timeuse < one_frame_us) {
            usleep(one_frame_us - timeuse);
        }
        gettimeofday(&t1, NULL);
    }

    if (frame_count > 0) {
        nvenc->WriteTrailer();
    }

    printf("do Close() thread(%d)\n", idx);
    nvenc->Close();  // Crash will occur
    printf("Closed thread(%d)\n", idx);
    delete nvenc;
    av_frame_free(&avframe_);
}


  


• Frames took with ELP camera has unknown pixel format at FHD ?

  11 novembre 2024, par Marcel Kopera

  I'm trying to take a one frame ever x seconds from my usb camera. Name of the camera is : ELP-USBFHD06H-SFV(5-50).
Code is not 100% done yet, but I'm using it this way right now ↓ (shot fn is called from main.py in a loop)

  


  
import cv2
import subprocess

from time import sleep
from collections import namedtuple

from errors import *

class Camera:
    def __init__(self, cam_index, res_width, res_height, pic_format, day_time_exposure_ms, night_time_exposure_ms):
        Resolution = namedtuple("resolution", ["width", "height"])
        self.manual_mode(True)

        self.cam_index = cam_index
        self.camera_resolution = Resolution(res_width, res_height)
        self.picture_format = pic_format
        self.day_time_exposure_ms = day_time_exposure_ms
        self.night_time_exposure_ms = night_time_exposure_ms

        self.started: bool = False
        self.night_mode = False

        self.cap = cv2.VideoCapture(self.cam_index, cv2.CAP_V4L2)
        self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, self.camera_resolution.width)
        self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, self.camera_resolution.height)
        self.cap.set(cv2.CAP_PROP_FOURCC, cv2.VideoWriter_fourcc(*self.picture_format))

    

    def start(self):
        sleep(1)
        if not self.cap.isOpened():
            return CameraCupError()

        self.set_exposure_time(self.day_time_exposure_ms)
        self.set_brightness(0)
        sleep(0.1)
        
        self.started = True



    def shot(self, picture_name, is_night):
        if not self.started:
            return InitializationError()

        self.configure_mode(is_night)

        # Clear buffer
        for _ in range(5):
            ret, _ = self.cap.read()

        ret, frame = self.cap.read()

        sleep(0.1)

        if ret:
            print(picture_name)
            cv2.imwrite(picture_name, frame)
            return True

        else:
            print("No photo")
            return False


    
    def release(self):
        self.set_exposure_time(156)
        self.set_brightness(0)
        self.manual_mode(False)
        self.cap.release()



    def manual_mode(self, switch: bool):
        if switch:
            subprocess.run(["v4l2-ctl", "--set-ctrl=auto_exposure=1"])
        else:
            subprocess.run(["v4l2-ctl", "--set-ctrl=auto_exposure=3"])
        sleep(1)

    
    
    def configure_mode(self, is_night):
        if is_night == self.night_mode:
            return

        if is_night:
            self.night_mode = is_night
            self.set_exposure_time(self.night_time_exposure_ms)
            self.set_brightness(64)
        else:
            self.night_mode = is_night
            self.set_exposure_time(self.day_time_exposure_ms)
            self.set_brightness(0)
        sleep(0.1)



    def set_exposure_time(self, ms: int):
        ms = int(ms)
        default_val = 156

        if ms < 1 or ms > 5000:
            ms = default_val

        self.cap.set(cv2.CAP_PROP_EXPOSURE, ms)



    def set_brightness(self, value: int):
        value = int(value)
        default_val = 0

        if value < -64 or value > 64:
            value = default_val

        self.cap.set(cv2.CAP_PROP_BRIGHTNESS, value)


  


  Here are settings for the camera (yaml file)

  


  camera:
  camera_index: 0
  res_width: 1920
  res_height: 1080
  picture_format: "MJPG"
  day_time_exposure_ms: 5
  night_time_exposure_ms: 5000
  photos_format: "jpg"



  


  I do some configs like set manual mode for the camera, change exposure/brightness and saving frame.
Also the camera is probably catching the frames to the buffer (it is not saving latest frame in real time : it's more laggish), so I have to clear buffer every time. like this

  


          # Clear buffer from old frames
        for _ in range(5):
            ret, _ = self.cap.read()
        
        # Get a new frame
        ret, frame = self.cap.read()


  


  What I really don't like, but I could find a better way (tldr : setting buffer for 1 frame doesn't work on my camera).

  


  Frames saved this method looks good with 1920x1080 resolution. BUT when I try to run ffmpeg command to make a timelapse from saved jpg file like this

  


  ffmpeg -framerate 20 -pattern_type glob -i "*.jpg" -c:v libx264 output.mp4


  


  I got an error like this one

  


  [image2 @ 0x555609c45240] Could not open file : 08:59:20.jpg
[image2 @ 0x555609c45240] Could not find codec parameters for stream 0 (Video: mjpeg, none(bt470bg/unknown/unknown)): unspecified size
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, image2, from '*.jpg':
  Duration: 00:00:00.05, start: 0.000000, bitrate: N/A
  Stream #0:0: Video: mjpeg, none(bt470bg/unknown/unknown), 20 fps, 20 tbr, 20 tbn
Output #0, mp4, to 'output.mp4':
Output file #0 does not contain any stream


  


  Also when I try to copy the files from Linux to Windows I get some weird copy failing error and option to skip the picture. But even when I press the skip button, the picture is copied and can be opened. I'm not sure what is wrong with the format, but the camera is supporting MPEG at 1920x1080.

  


  >>> v4l2-ctl --all

Driver Info:
        Driver name      : uvcvideo
        Card type        : H264 USB Camera: USB Camera
        Bus info         : usb-xhci-hcd.1-1
        Driver version   : 6.6.51
        Capabilities     : 0x84a00001
                Video Capture
                Metadata Capture
                Streaming
                Extended Pix Format
                Device Capabilities
        Device Caps      : 0x04200001
                Video Capture
                Streaming
                Extended Pix Format
Media Driver Info:
        Driver name      : uvcvideo
        Model            : H264 USB Camera: USB Camera
        Serial           : 2020032801
        Bus info         : usb-xhci-hcd.1-1
        Media version    : 6.6.51
        Hardware revision: 0x00000100 (256)
        Driver version   : 6.6.51
Interface Info:
        ID               : 0x03000002
        Type             : V4L Video
Entity Info:
        ID               : 0x00000001 (1)
        Name             : H264 USB Camera: USB Camera
        Function         : V4L2 I/O
        Flags            : default
        Pad 0x0100000d   : 0: Sink
          Link 0x0200001a: from remote pad 0x1000010 of entity 'Extension 4' (Video Pixel Formatter): Data, Enabled, Immutable
Priority: 2
Video input : 0 (Camera 1: ok)
Format Video Capture:
        Width/Height      : 1920/1080
        Pixel Format      : 'MJPG' (Motion-JPEG)
        Field             : None
        Bytes per Line    : 0
        Size Image        : 4147789
        Colorspace        : sRGB
        Transfer Function : Default (maps to sRGB)
        YCbCr/HSV Encoding: Default (maps to ITU-R 601)
        Quantization      : Default (maps to Full Range)
        Flags             :
Crop Capability Video Capture:
        Bounds      : Left 0, Top 0, Width 1920, Height 1080
        Default     : Left 0, Top 0, Width 1920, Height 1080
        Pixel Aspect: 1/1
Selection Video Capture: crop_default, Left 0, Top 0, Width 1920, Height 1080, Flags:
Selection Video Capture: crop_bounds, Left 0, Top 0, Width 1920, Height 1080, Flags:
Streaming Parameters Video Capture:
        Capabilities     : timeperframe
        Frames per second: 15.000 (15/1)
        Read buffers     : 0

User Controls

                     brightness 0x00980900 (int)    : min=-64 max=64 step=1 default=0 value=64
                       contrast 0x00980901 (int)    : min=0 max=64 step=1 default=32 value=32
                     saturation 0x00980902 (int)    : min=0 max=128 step=1 default=56 value=56
                            hue 0x00980903 (int)    : min=-40 max=40 step=1 default=0 value=0
        white_balance_automatic 0x0098090c (bool)   : default=1 value=1
                          gamma 0x00980910 (int)    : min=72 max=500 step=1 default=100 value=100
                           gain 0x00980913 (int)    : min=0 max=100 step=1 default=0 value=0
           power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=1 value=1 (50 Hz)
                                0: Disabled
                                1: 50 Hz
                                2: 60 Hz
      white_balance_temperature 0x0098091a (int)    : min=2800 max=6500 step=1 default=4600 value=4600 flags=inactive
                      sharpness 0x0098091b (int)    : min=0 max=6 step=1 default=3 value=3
         backlight_compensation 0x0098091c (int)    : min=0 max=2 step=1 default=1 value=1

Camera Controls

                  auto_exposure 0x009a0901 (menu)   : min=0 max=3 default=3 value=1 (Manual Mode)
                                1: Manual Mode
                                3: Aperture Priority Mode
         exposure_time_absolute 0x009a0902 (int)    : min=1 max=5000 step=1 default=156 value=5000
     exposure_dynamic_framerate 0x009a0903 (bool)   : default=0 value=0


  


  I also tried to save the picture using ffmpeg in a case something is not right with opencv like this :

  


  ffmpeg -f v4l2 -framerate 30 -video_size 1920x1080 -i /dev/video0 -c:v libx264 -preset fast -crf 23 -t 00:01:00 output.mp4



  


  It is saving the picture but also changing its format

  


  [video4linux2,v4l2 @ 0x555659ed92b0] The V4L2 driver changed the video from 1920x1080 to 800x600
[video4linux2,v4l2 @ 0x555659ed92b0] The driver changed the time per frame from 1/30 to 1/15


  


  But the format looks right when set it back to FHD using v4l2

  


  
>>> v4l2-ctl --device=/dev/video0 --set-fmt-video=width=1920,height=1080,pixelformat=MJPG
>>> v4l2-ctl --get-fmt-video

Format Video Capture:
        Width/Height      : 1920/1080
        Pixel Format      : 'MJPG' (Motion-JPEG)
        Field             : None
        Bytes per Line    : 0
        Size Image        : 4147789
        Colorspace        : sRGB
        Transfer Function : Default (maps to sRGB)
        YCbCr/HSV Encoding: Default (maps to ITU-R 601)
        Quantization      : Default (maps to Full Range)
        Flags             :


  


  I'm not sure what could be wrong with the format/camera and I don't think I have enough information to figure it out.

  


  I tried to use ffmpeg instead of opencv and also change a few settings in opencv's cup config.

  


• Problems using libavfilter for adding overlay to frames

  12 novembre 2024, par Michael Werner

  On Windows 11 OS with latest libav (full build) a C/C++ app reads YUV420P frames from a frame grabber card.

  


  I want to draw a bitmap (BGR24) overlay image from file on every frame via libavfilter. First I convert the BGR24 overlay image via format filter to YUV420P. Then I feed the YUV420P frame from frame grabber and the YUV420P overlay into the overlay filter.

  


  Everything seems to be fine but when I try to get the frame out of the filter graph I always get an "Resource is temporary not available" (EAGAIN) return code, independent on how many frames I put into the graph.

  


  The frames from the frame grabber card are fine, I could encode them or write them to a .yuv file. The overlay frame looks fine too.

  


  My current initialization code looks like below. It does not report any errors or warnings but when I try to get the filtered frame out of the graph via av_buffersink_get_frame I always get an EAGAIN return code.

  


  Here is my current initialization code :

  


  int init_overlay_filter(AVFilterGraph** graph, AVFilterContext** src_ctx, AVFilterContext** overlay_src_ctx,
                        AVFilterContext** sink_ctx)
{
    AVFilterGraph* filter_graph;
    AVFilterContext* buffersrc_ctx;
    AVFilterContext* overlay_buffersrc_ctx;
    AVFilterContext* buffersink_ctx;
    AVFilterContext* overlay_ctx;
    AVFilterContext* format_ctx;
    const AVFilter *buffersrc, *buffersink, *overlay_buffersrc, *overlay_filter, *format_filter;
    int ret;

    // Create the filter graph
    filter_graph = avfilter_graph_alloc();
    if (!filter_graph)
    {
        fprintf(stderr, "Unable to create filter graph.\n");
        return AVERROR(ENOMEM);
    }

    // Create buffer source filter for main video
    buffersrc = avfilter_get_by_name("buffer");
    if (!buffersrc)
    {
        fprintf(stderr, "Unable to find buffer filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create buffer source filter for overlay image
    overlay_buffersrc = avfilter_get_by_name("buffer");
    if (!overlay_buffersrc)
    {
        fprintf(stderr, "Unable to find buffer filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create buffer sink filter
    buffersink = avfilter_get_by_name("buffersink");
    if (!buffersink)
    {
        fprintf(stderr, "Unable to find buffersink filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create overlay filter
    overlay_filter = avfilter_get_by_name("overlay");
    if (!overlay_filter)
    {
        fprintf(stderr, "Unable to find overlay filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Create format filter
    format_filter = avfilter_get_by_name("format");
    if (!format_filter) 
    {
        fprintf(stderr, "Unable to find format filter.\n");
        return AVERROR_FILTER_NOT_FOUND;
    }

    // Initialize the main video buffer source
    char args[512];
    snprintf(args, sizeof(args),
             "video_size=1920x1080:pix_fmt=yuv420p:time_base=1/25:pixel_aspect=1/1");
    ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in", args, NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer source filter for main video.\n");
        return ret;
    }

    // Initialize the overlay buffer source
    snprintf(args, sizeof(args),
             "video_size=165x165:pix_fmt=bgr24:time_base=1/25:pixel_aspect=1/1");
    ret = avfilter_graph_create_filter(&overlay_buffersrc_ctx, overlay_buffersrc, "overlay_in", args, NULL,
                                       filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer source filter for overlay.\n");
        return ret;
    }

    // Initialize the format filter to convert overlay image to yuv420p
    snprintf(args, sizeof(args), "pix_fmts=yuv420p");
    ret = avfilter_graph_create_filter(&format_ctx, format_filter, "format", args, NULL, filter_graph);

    if (ret < 0) 
    {
        fprintf(stderr, "Unable to create format filter.\n");
        return ret;
    }

    // Initialize the buffer sink
    ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out", NULL, NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create buffer sink filter.\n");
        return ret;
    }

    // Initialize the overlay filter
    ret = avfilter_graph_create_filter(&overlay_ctx, overlay_filter, "overlay", "W-w:H-h:enable='between(t,0,20)':format=yuv420", NULL, filter_graph);
    if (ret < 0)
    {
        fprintf(stderr, "Unable to create overlay filter.\n");
        return ret;
    }

    // Connect the filters
    ret = avfilter_link(overlay_buffersrc_ctx, 0, format_ctx, 0);

    if (ret >= 0)
    {
        ret = avfilter_link(buffersrc_ctx, 0, overlay_ctx, 0);
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }


    if (ret >= 0) 
    {
        ret = avfilter_link(format_ctx, 0, overlay_ctx, 1);
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    if (ret >= 0) 
    {
        if ((ret = avfilter_link(overlay_ctx, 0, buffersink_ctx, 0)) < 0)
        {
            fprintf(stderr, "Unable to link filter graph.\n");
            return ret;
        }
    }
    else
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    // Configure the filter graph
    if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
    {
        fprintf(stderr, "Unable to configure filter graph.\n");
        return ret;
    }

    *graph = filter_graph;
    *src_ctx = buffersrc_ctx;
    *overlay_src_ctx = overlay_buffersrc_ctx;
    *sink_ctx = buffersink_ctx;

    return 0;
}


  


  Feeding the filter graph is done this way :

  


  av_buffersrc_add_frame_flags(buffersrc_ctx, pFrameGrabberFrame, AV_BUFFERSRC_FLAG_KEEP_REF)
av_buffersink_get_frame(buffersink_ctx, filtered_frame)


  


  av_buffersink_get_frame returns always EAGAIN, no matter how many frames I feed into the graph. The frames (from framegrabber and the overlay frame) itself are looking fine.

  


  I did set libav logging level to maximum but I do not see any warnings or errors or helpful, related information in the log.

  


  Here the log output related to the filter configuration :

  


  [in @ 00000288ee494f40] Setting 'video_size' to value '1920x1080'
[in @ 00000288ee494f40] Setting 'pix_fmt' to value 'yuv420p'
[in @ 00000288ee494f40] Setting 'time_base' to value '1/25'
[in @ 00000288ee494f40] Setting 'pixel_aspect' to value '1/1'
[in @ 00000288ee494f40] w:1920 h:1080 pixfmt:yuv420p tb:1/25 fr:0/1 sar:1/1 csp:unknown range:unknown
[overlay_in @ 00000288ff1013c0] Setting 'video_size' to value '165x165'
[overlay_in @ 00000288ff1013c0] Setting 'pix_fmt' to value 'bgr24'
[overlay_in @ 00000288ff1013c0] Setting 'time_base' to value '1/25'
[overlay_in @ 00000288ff1013c0] Setting 'pixel_aspect' to value '1/1'
[overlay_in @ 00000288ff1013c0] w:165 h:165 pixfmt:bgr24 tb:1/25 fr:0/1 sar:1/1 csp:unknown range:unknown
[format @ 00000288ff1015c0] Setting 'pix_fmts' to value 'yuv420p'
[overlay @ 00000288ff101880] Setting 'x' to value 'W-w'
[overlay @ 00000288ff101880] Setting 'y' to value 'H-h'
[overlay @ 00000288ff101880] Setting 'enable' to value 'between(t,0,20)'
[overlay @ 00000288ff101880] Setting 'format' to value 'yuv420'
[auto_scale_0 @ 00000288ff101ec0] w:iw h:ih flags:'' interl:0
[format @ 00000288ff1015c0] auto-inserting filter 'auto_scale_0' between the filter 'overlay_in' and the filter 'format'
[auto_scale_1 @ 00000288ee4a4cc0] w:iw h:ih flags:'' interl:0
[overlay @ 00000288ff101880] auto-inserting filter 'auto_scale_1' between the filter 'format' and the filter 'overlay'
[AVFilterGraph @ 00000288ee495c80] query_formats: 5 queried, 6 merged, 6 already done, 0 delayed
[auto_scale_0 @ 00000288ff101ec0] w:165 h:165 fmt:bgr24 csp:gbr range:pc sar:1/1 -> w:165 h:165 fmt:yuv420p csp:unknown range:unknown sar:1/1 flags:0x00000004
[auto_scale_1 @ 00000288ee4a4cc0] w:165 h:165 fmt:yuv420p csp:unknown range:unknown sar:1/1 -> w:165 h:165 fmt:yuva420p csp:unknown range:unknown sar:1/1 flags:0x00000004
[overlay @ 00000288ff101880] main w:1920 h:1080 fmt:yuv420p overlay w:165 h:165 fmt:yuva420p
[overlay @ 00000288ff101880] [framesync @ 00000288ff1019a8] Selected 1/25 time base
[overlay @ 00000288ff101880] [framesync @ 00000288ff1019a8] Sync level 2