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• how Youtube Ios app is playing 1080p and above ?

  19 septembre 2018, par user10387397

  I have been going through video codecs and ffmpeg .

  Understood everything between vp9 , HEVC(h.265) and H264 , webm dash streaming , and hls streaming.

  As far as i have read and understood that youtube stopped encoding for 1080p and higher in H264 and made it available only in webm VP9. Thus safari is limited by 720p.

  However, in IOS native app of youtube , they are providing 1080p and 1440p . Are they encoding it in different format ?

  The main question i would want to ask is how are they able to play 1080p and above in ios app when they were encoding this only in VP9 webm , whereas ios doesnot support VP9.

• How to set ffmpeg qscale in C/C++ for image encoding

  4 juillet 2022, par necrosato

  I have a working image encoder in C++ using ffmpeg as the backend. I am taking videos in and saving frames out as jpeg, but I am having difficulty adjusting the quality of the output jpegs.
  
Things I have tried :
  
Setting AVCodecContext's global_quality and compression_level fields.
  
I have also tried setting qscale with an AVDictionary of options, but have been unsuccessful there too.

  



  I know its possible because with the command line I can
  
ffmpeg -i INPUT -q:v 2 output_frame_%02d.jpg and get higher quality images.

  


• After upgrade ffmpeg code doesn't working clip build

  11 février, par Tchoune

  I have a problem after upgrading ffmpeg from 4.2.2 to 5.2.2, my code no longer works. When I upload a video to my React-Native application I get a file corruption error on my FFmpeg python agent.
-> sends to Laravel which stores the video on the minio storage ; the video is available -> sends http to the minio key to download locally the mp4 video is corrupted on the minio too...
I have the impression that it's an error downloading the video locally that makes the video corrupt, but I have no idea how I can debug this problem.
If I upload the video directly from my web interface I don't have this problem. The only difference is processClipSynchronously which is set to True on mobile and False on web.

  


  Laravel Agent send to python microservice :

  


   // Store uploaded video file
        $videoFilePath = $this->storeVideoFile($learningGoal, $videoFile);

        // Add video to storyboard
        $agentResponse =  Http::post($this->agentUrl . 'learning-goals/' . $learningGoal->id . '/storyboards/' . $storyboardId .  '/chapters/' . $chapterId . '/videos',
            [
                'clip' => $videoFilePath,
                'processClipSynchronously' => $processClipSynchronously
            ]);


  


  Python agent video :

  


  @app.route('/learning-goals//storyboards//chapters//videos',
           methods=['post'])
def post_storyboard_videos(learning_goal_id, storyboard_id, chapter_id):
    storyboard = get_storyboard(learning_goal_id, storyboard_id)
    chapter, position = get_chapter(storyboard, chapter_id)

    if 'clip' in request.get_json():
        chapter['clip'] = request.get_json()['clip']
        if 'duration' in storyboard:
            del chapter['duration']
        if 'thumbnail' in storyboard:
            del chapter['thumbnail']
        if 'ncAudioPreviewPath' in chapter:
            del chapter['ncAudioPreviewPath']
        if 'trim_start' in chapter:
            del chapter['trim_start']
        if 'trim_end' in chapter:
            del chapter['trim_end']
        if 'perform_nc' in chapter:
            del chapter['perform_nc']
    else:
        abort(400)

    new_storyboard = create_new_version_storyboard(storyboard)

    if 'processClipSynchronously' in request.get_json() and request.get_json()['processClipSynchronously']:
        treat_clip(new_storyboard, chapter) #Mobile trigger here
    else:
        thread = StoppableThread(target=treat_clip, args=(new_storyboard, chapter))
        thread.daemon = True
        thread.start()

    chapter, position = get_chapter(new_storyboard, chapter_id)

    return json.loads(dumps(chapter))

def treat_clip(storyboard, chapter):
    logging.info(
        'start treating clip (' + chapter['clip'] + ') for learning goal : ' + str(storyboard['learningGoalId']))
    file = app.config['VOLUME_PATH'] + chapter['clip']
    os.makedirs(dirname(file), exist_ok=True)
    temp_files_to_remove = []

    if not os.path.exists(file):
        # Download file from S3 storage.
        s3.download_file(chapter['clip'], file)
        # Clean the file at the end (it's already in S3).
        temp_files_to_remove.append(file)
    else:
        logging.warn(f'Not downloading {chapter["clip"]} from S3 as it already exists on the filesystem')

    resolution_width, resolution_height = get_resolution(file)
    is_rotated_video = is_rotated(file)
    sample_aspect_ratio = get_sample_aspect_ratio(file)
    frame_rate = get_frame_rate(file)
    if not file.endswith(
            '.mp4') or resolution_width != 1920 or resolution_height != 1080 or is_rotated_video or sample_aspect_ratio != '1:1' or frame_rate > 60:
        chapter['clip'] = format_video(chapter['clip'], resolution_width, resolution_height, frame_rate,
                                       is_rotated_video, str(storyboard['learningGoalId']), 1920, 1080)
        file = app.config['VOLUME_PATH'] + chapter['clip']

        # Update file to S3 storage
        s3.upload_file(file, chapter['clip'])

        # Clean the new file at the end.
        temp_files_to_remove.append(file)

    clip = VideoFileClip(file)
    chapter['duration'] = float(clip.duration)
    thumbnail_relative_path = create_video_thumbnail(storyboard, clip, 0)
    ....


  


  It's VideoFileClip from moviepy who generate error : Moov atom not found
I think S3 not have time to download file, and corrumpt, but I don't know how to test or fix that

  


  thanks in advance