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• Basic "pass-through" use of FFmpegReader/FFmpegWriter in scikit-video

  6 février 2021, par JonathanZ supports MonicaC

  I am starting to use scikit-video and am having trouble writing files. I have reduced the problem to the simplest possible example

  


  vid_file = "6710185719062326259_stamp_25pct.mp4"
output_file = "out_temp3.mp4"
reader = skvideo.io.FFmpegReader(vid_file)
writer = skvideo.io.FFmpegWriter(output_file)
for frame in reader.nextFrame():
        writer.writeFrame(frame)
writer.close()


  


  I'm playing the files in VLC, and the vid_file is valid but the output file, though playable, is mostly big green blocks (though I can discern some details from the original video in it).

  


  My goal, or course, is to do "interesting" manipulations of the frame before I write it out, but I need to get the "no modifications" version working correctly first. I'm also going to be using this on large files, so the vread/vwrite functions that process an entire file at once are not appropriate.

  


  I'm guessing I need to set the appropriate values in the outputdict parameter for the FFmpegWriter, but there are so many that I don't know where to start. I have tried

  


  writer = skvideo.io.FFmpegWriter(output_file, outputdict={'-crf': '0', '-pix_fmt': 'rgb24'})


  


  (-crf 0 to suppress any compression, -pixfmt rgb24 as that's what FFmpegReader says it delivers by default, but these don't work either.

  


  Any ideas on how to make this work ?

  


  Here's the skvideo.io.ffprobe video information for the input file.

  


  {
    "@index": "0",
    "@codec_name": "h264",
    "@codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
    "@profile": "High",
    "@codec_type": "video",
    "@codec_time_base": "1/30",
    "@codec_tag_string": "avc1",
    "@codec_tag": "0x31637661",
    "@width": "480",
    "@height": "270",
    "@coded_width": "480",
    "@coded_height": "272",
    "@has_b_frames": "2",
    "@pix_fmt": "yuv420p",
    "@level": "21",
    "@chroma_location": "left",
    "@refs": "1",
    "@is_avc": "true",
    "@nal_length_size": "4",
    "@r_frame_rate": "15/1",
    "@avg_frame_rate": "15/1",
    "@time_base": "1/15360",
    "@start_pts": "0",
    "@start_time": "0.000000",
    "@duration_ts": "122880",
    "@duration": "8.000000",
    "@bit_rate": "183806",
    "@bits_per_raw_sample": "8",
    "@nb_frames": "120",
    "disposition": {
        "@default": "1",
        "@dub": "0",
        "@original": "0",
        "@comment": "0",
        "@lyrics": "0",
        "@karaoke": "0",
        "@forced": "0",
        "@hearing_impaired": "0",
        "@visual_impaired": "0",
        "@clean_effects": "0",
        "@attached_pic": "0",
        "@timed_thumbnails": "0"
    },
    "tag": [
        {
            "@key": "language",
            "@value": "und"
        },
        {
            "@key": "handler_name",
            "@value": "VideoHandler"
        }
    ]
}


  


  I will mention that when I ffprobe the output file the only differences I see are 1) the timing data is different, which isn't surprising, and 2) the output file has

  


      "@has_b_frames": "0",
    "@pix_fmt": "yuv444p",


  


  I'm pretty confident the reader is working okay, because if I write out the data with

  


  skimage.io.imsave('x.png', frame,  check_contrast=False)


  


  it looks good.

  


• ffmpeg/ffprobe get HLS 'codecs' string for a video/audio stream

  19 décembre 2020, par Richard

  I'm using ffmpeg to create HLS sub-playlists. I used ffmpeg to create them for the renditions. Now I need to create the master playlist .m3u8.

  


  I need to do this manually, for a few reasons. I have everything I need except the 'CODECS' value.

  


  How can I get this CODECS value for the video and audio streams within my file ?

  


  I cannot see the relevant data when I use ffprobe to get all the metadata about the streams.

  


  Example master manifest with CODECS :

  


  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:BANDWIDTH=540863,RESOLUTION=640x360,CODECS="avc1.64001e,mp4a.40.2"
v0/prog_index.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=2339363,RESOLUTION=960x540,CODECS="avc1.64001f,mp4a.40.2"
v1/prog_index.m3u8


  


  Example of metadata I could get using ffprobe :

  


  {'avg_frame_rate': '24000/1001',
 'bit_rate': '35956',
 'bits_per_raw_sample': '8',
 'chroma_location': 'left',
 'closed_captions': 0,
 'codec_long_name': 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
 'codec_name': 'h264',
 'codec_tag': '0x31637661',
 'codec_tag_string': 'avc1',
 'codec_time_base': '1001/48000',
 'codec_type': 'video',
 'coded_height': 368,
 'coded_width': 640,
 'display_aspect_ratio': '16:9',
 'disposition': {'attached_pic': 0,
                 'clean_effects': 0,
                 'comment': 0,
                 'default': 1,
                 'dub': 0,
                 'forced': 0,
                 'hearing_impaired': 0,
                 'karaoke': 0,
                 'lyrics': 0,
                 'original': 0,
                 'timed_thumbnails': 0,
                 'visual_impaired': 0},
 'duration': '5.005000',
 'duration_ts': 120120,
 'has_b_frames': 2,
 'height': 360,
 'index': 0,
 'is_avc': 'true',
 'level': 30,
 'nal_length_size': '4',
 'nb_frames': '120',
 'pix_fmt': 'yuv420p',
 'profile': 'High',
 'r_frame_rate': '24000/1001',
 'refs': 1,
 'sample_aspect_ratio': '1:1',
 'start_pts': 0,
 'start_time': '0.000000',
 'tags': {'handler_name': 'VideoHandler',
          'language': 'eng',
          'timecode': '01:00:00:00'},
 'time_base': '1/24000',
 'width': 640}


  


  {'avg_frame_rate': '0/0',
 'bit_rate': '138375',
 'bits_per_sample': 0,
 'channel_layout': 'stereo',
 'channels': 2,
 'codec_long_name': 'AAC (Advanced Audio Coding)',
 'codec_name': 'aac',
 'codec_tag': '0x6134706d',
 'codec_tag_string': 'mp4a',
 'codec_time_base': '1/48000',
 'codec_type': 'audio',
 'disposition': {'attached_pic': 0,
                 'clean_effects': 0,
                 'comment': 0,
                 'default': 1,
                 'dub': 0,
                 'forced': 0,
                 'hearing_impaired': 0,
                 'karaoke': 0,
                 'lyrics': 0,
                 'original': 0,
                 'timed_thumbnails': 0,
                 'visual_impaired': 0},
 'duration': '5.005000',
 'duration_ts': 240240,
 'index': 1,
 'max_bit_rate': '138375',
 'nb_frames': '236',
 'profile': 'LC',
 'r_frame_rate': '0/0',
 'sample_fmt': 'fltp',
 'sample_rate': '48000',
 'start_pts': 0,
 'start_time': '0.000000',
 'tags': {'handler_name': 'SoundHandler', 'language': 'eng'},
 'time_base': '1/48000'}


  


• ffmpeg/ffprobe get 'codecs' string for a video/audio stream

  18 décembre 2020, par Richard

  I'm using ffmpeg to create HLS playlists. I used ffmpeg to create them for the renditions. Now I need to create the master playlist .m3u8.

  


  I need to do this manually, for a few reasons. I have everything I need except the 'CODECS' value.

  


  How can I get this CODECS value for the video and audio streams within my file ?

  


  I cannot see the relevant data when I use ffprobe to get all the metadata about the streams.

  


  Example master manifest with CODECS :

  


  #EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:BANDWIDTH=540863,RESOLUTION=640x360,CODECS="avc1.64001e,mp4a.40.2"
v0/prog_index.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=2339363,RESOLUTION=960x540,CODECS="avc1.64001f,mp4a.40.2"
v1/prog_index.m3u8


  


  Example of metadata I could get using ffprobe :

  


  {'avg_frame_rate': '24000/1001',
 'bit_rate': '35956',
 'bits_per_raw_sample': '8',
 'chroma_location': 'left',
 'closed_captions': 0,
 'codec_long_name': 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
 'codec_name': 'h264',
 'codec_tag': '0x31637661',
 'codec_tag_string': 'avc1',
 'codec_time_base': '1001/48000',
 'codec_type': 'video',
 'coded_height': 368,
 'coded_width': 640,
 'display_aspect_ratio': '16:9',
 'disposition': {'attached_pic': 0,
                 'clean_effects': 0,
                 'comment': 0,
                 'default': 1,
                 'dub': 0,
                 'forced': 0,
                 'hearing_impaired': 0,
                 'karaoke': 0,
                 'lyrics': 0,
                 'original': 0,
                 'timed_thumbnails': 0,
                 'visual_impaired': 0},
 'duration': '5.005000',
 'duration_ts': 120120,
 'has_b_frames': 2,
 'height': 360,
 'index': 0,
 'is_avc': 'true',
 'level': 30,
 'nal_length_size': '4',
 'nb_frames': '120',
 'pix_fmt': 'yuv420p',
 'profile': 'High',
 'r_frame_rate': '24000/1001',
 'refs': 1,
 'sample_aspect_ratio': '1:1',
 'start_pts': 0,
 'start_time': '0.000000',
 'tags': {'handler_name': 'VideoHandler',
          'language': 'eng',
          'timecode': '01:00:00:00'},
 'time_base': '1/24000',
 'width': 640}


  


  {'avg_frame_rate': '0/0',
 'bit_rate': '138375',
 'bits_per_sample': 0,
 'channel_layout': 'stereo',
 'channels': 2,
 'codec_long_name': 'AAC (Advanced Audio Coding)',
 'codec_name': 'aac',
 'codec_tag': '0x6134706d',
 'codec_tag_string': 'mp4a',
 'codec_time_base': '1/48000',
 'codec_type': 'audio',
 'disposition': {'attached_pic': 0,
                 'clean_effects': 0,
                 'comment': 0,
                 'default': 1,
                 'dub': 0,
                 'forced': 0,
                 'hearing_impaired': 0,
                 'karaoke': 0,
                 'lyrics': 0,
                 'original': 0,
                 'timed_thumbnails': 0,
                 'visual_impaired': 0},
 'duration': '5.005000',
 'duration_ts': 240240,
 'index': 1,
 'max_bit_rate': '138375',
 'nb_frames': '236',
 'profile': 'LC',
 'r_frame_rate': '0/0',
 'sample_fmt': 'fltp',
 'sample_rate': '48000',
 'start_pts': 0,
 'start_time': '0.000000',
 'tags': {'handler_name': 'SoundHandler', 'language': 'eng'},
 'time_base': '1/48000'}