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• Crash on ffmpeg avcodec_encode_video in a Console app [closed]

  11 janvier 2024, par Robel Sharma

  I want make an encoder which encode a raw image into h263 format.But after loading and initializing ffmpeg library I got crash on avcodec_encode_video for a demo image.

  



  int _tmain(int argc, _TCHAR* argv[]) {
    avcodec_register_all();
    AVCodec *codec;
    AVCodecContext *c= NULL;
    int i, ret, x, y, got_output;
    FILE *f;
    AVFrame *frame;
    AVPacket pkt;

    int out_size, size, outbuf_size;

    AVFrame *picture;
    uint8_t *outbuf, *picture_buf;

    AVRational rp;   

    rp.den = 1;
    rp.num = 25;
    uint8_t endcode[] = { 0, 0, 1, 0xb7 };

    codec = avcodec_find_encoder(CODEC_ID_H263);

    c = avcodec_alloc_context3(codec);
    picture= avcodec_alloc_frame();
    c->bit_rate = 400000;
    /* resolution must be a multiple of two */
    c->width = 352;
    c->height = 288;
    /* frames per second */
    //c->time_base= (AVRational){1,25};
    c->time_base = rp;
    c->gop_size = 10; /* emit one intra frame every ten frames */
    c->max_b_frames=1;
    c->pix_fmt = PIX_FMT_YUV420P;
    avcodec_open(c, codec);


    outbuf_size = 100000;
    outbuf = (uint8_t*)malloc(outbuf_size);
    size = c->width * c->height;
    picture_buf = (uint8_t*)malloc((size * 3) / 2); /* size for YUV 420 */

    picture->data[0] = picture_buf;
    picture->data[1] = picture->data[0] + size;
    picture->data[2] = picture->data[1] + size / 4;
    picture->linesize[0] = c->width;
    picture->linesize[1] = c->width / 2;
    picture->linesize[2] = c->width / 2;

    /* encode 1 second of video */
    for(i=0;i<25;i++) {
        fflush(stdout);
        /* prepare a dummy image */
        /* Y */
        for(y=0;yheight;y++) {
            for(x=0;xwidth;x++) {
                picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
            }
        }
        /* Cb and Cr */
        for(y=0;yheight/2;y++) {
            for(x=0;xwidth/2;x++) {
                picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
                picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
            }
        }
        /* encode the image */

        **Crash is here** --->                 ///////////////////////////////////////////////////
        out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);

        printf("encoding frame %3d (size=%5d)\n", i, out_size);
        fwrite(outbuf, 1, out_size, f);
    }
    /* get the delayed frames */
    for(; out_size; i++) {
        fflush(stdout);
        out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
        printf("write frame %3d (size=%5d)\n", i, out_size);
        fwrite(outbuf, 1, out_size, f);
    }
    /* add sequence end code to have a real mpeg file */
    outbuf[0] = 0x00;
    outbuf[1] = 0x00;
    outbuf[2] = 0x01;
    outbuf[3] = 0xb7;
    fwrite(outbuf, 1, 4, f);
    fclose(f);
    free(picture_buf);
    free(outbuf);

    avcodec_close(c);
    av_free(c);
    av_free(picture);
    printf("\n");
    return 0;
}


  


• ffmpeg doesn't generate a ISO/IEC 14496-17 (MPEG-4 text) track when ingesting WebVTT subtitles to produce MPEGTS

  10 avril 2024, par Daniel Andres Pelaez Lopez

  We are trying to create a mpegts with an ISO/IEC 14496-17 (MPEG-4 text) subtitles track, using WebVTT, but seems like ffmpeg creates a ISO 13818-1 PES private data instead.

  


  The following is the ffmpeg command :

  


  ffmpeg -i subtitle.vtt -c:s mov_text -f mpegts output3GPP.ts

  


  This is using the following subtitle.vtt file :

  


  WEBVTT

00:00.000 --> 00:01.000
Subtitle 1

00:01.000 --> 00:02.000
Subtitle 2

00:02.000 --> 00:03.000
Subtitle 3

00:03.000 --> 00:04.000
Subtitle 4


  


  And the following is the output of the ffprobe for that file :

  


  Input #0, mpegts, from 'output3GPP.ts':
  Duration: 00:00:19.00, start: 1.400000, bitrate: 1 kb/s
  Program 1
    Metadata:
      service_name    : Service01
      service_provider: FFmpeg
  Stream #0:0[0x100]: Data: bin_data ([6][0][0][0] / 0x0006)
Unsupported codec with id 98314 for input stream 0


  


  However, if we generate an mp4, it works, the following is the command :

  


  ffmpeg -i subtitle.vtt -c:s mov_text -f mp4 output3GPP.ts

  


  And the following is the output of the ffprobe for that file :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output3GPP.ts':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf57.83.100
  Duration: 00:00:20.00, start: 0.000000, bitrate: 0 kb/s
  Stream #0:0[0x1](und): Subtitle: mov_text (tx3g / 0x67337874), 0
kb/s (default)
    Metadata:
      handler_name    : SubtitleHandler


  


  Any reason why both commands behave differently ? is mpegts not supporting ISO/IEC 14496-17 (MPEG-4 text) ?

  


• Transcoding Videos Using FastAPI and ffmpeg

  15 janvier 2024, par Sanji Vinsmoke

  I created an API using Fast API where I upload one or more videos, may specify the resolution of transcoding, and the output is transcoded video from 240p upto the resolution I specified. Available resolutions are - 240p, 360p, 480p, 720p, 1080p. I used ffmpeg for the transcoding job.

  


  The problem that is bugging me since yesterday is that, after deploying to the s3 bucket and adding the url for the index.m3u8 file in any hls player, the video is blank. Only the audio and streaming are working. I have tried tweaking with the parameters in the ffmpeg parameters, the error is still there. I tried manually transcoding a video file locally, even that video's index.m3u8 file is blank in live version. I added the relevant codes for this project. I implemented each feature one by one, but I simply cannot find the reason why the video is totally blank on live.

  


  def transcode_video(input_path, output_folder, res, video_id, video_resolution, progress_bar=None):
    # Transcode the video into .m3u8 format with segment format
    output_path = os.path.join(output_folder, f"{res}_{video_id}.m3u8")

    # Use subprocess for command execution
    chunk_size = 1 # Specify the desired chunk size in seconds

    transcode_command = [
        "ffmpeg", "-i", input_path, "-vf", f"scale={res}:'trunc(ow/a/2)*2'", "-c:a", "aac", "-strict", "-2",
        "-f", "segment", "-segment_time", str(chunk_size), "-segment_list", output_path, "-segment_format", "ts",
        f"{output_path.replace('.m3u8', '_%03d.ts')}"
    ]

    try:
        subprocess.run(transcode_command, check=True, capture_output=True)
    except subprocess.CalledProcessError as e:
        print(f"Error during transcoding: {e}")
        print(f"FFmpeg error output: {e.stderr}")
        # Continue with the next video even if an error occurs
        return False

    # Update the progress bar
    if progress_bar:
        progress_bar.update(1)
    return True


def get_bandwidth(resolution):
    # Define a simple function to calculate bandwidth based on resolution
    resolutions_and_bandwidths = {
        240: 400000,
        360: 850000,
        480: 1400000,
        720: 2500000,
        1080: 4500000,
    }
    
    return resolutions_and_bandwidths.get(resolution, 0)
def create_index_m3u8(video_id, resolutions_to_transcode):
    # Write the index.m3u8 file
    index_m3u8_path = os.path.join(OUTPUT_FOLDER, f"index_{video_id}.m3u8")
    with open(index_m3u8_path, "w") as index_file:
        index_file.write("#EXTM3U\n")
        index_file.write("#EXT-X-VERSION:3\n")

        for res in resolutions_to_transcode:
            aspect_ratio = 16 / 9
            folder_name = f"{res}p_{video_id}"
            resolution_file_name = f"{res}_{video_id}.m3u8"
            index_file.write(
                f"#EXT-X-STREAM-INF:BANDWIDTH={get_bandwidth(res)},RESOLUTION={int(res * aspect_ratio)}x{res}\n{folder_name}/{resolution_file_name}\n"
            )


  


  I tried reducing or increasing chunk size, adding codecs, setting up dimensions. Where am I doing wrong ?

  


  My python version is 3.8.18, ffmpeg version-4.4.4, ffmpeg-python version-0.2.0