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• ffmpeg transcoding : Metallic distorsion on macOS

  10 septembre 2024, par Xavi

  I am following ffmpeg's transcoding.c example to record audio and video from my input devices into an mp4 output file with H264 and AAC as codecs. I have no issues with the video and the audio transcoding works correctly on Windows.

  


  However, on macOS I have an issue with any input device other than the internal microphone of my laptop : the audio comes out distorted and sounding noisy and metallic (sample recording claps : https://file.io/nEn8MXHUAUQ2). I went through the input and output parameters for the filter several times, checked the values, but there must be something I'm missing. And I can't explain why it works on Windows with the same devices.

  


  Has anyone run into a similar problem before ? Any idea where I should start looking at ?

  


  Additional comments :

  


  

  1. While the Macbook's internal microphone (the only one that works) has only one channel, the other microphones I have available are stereo, so I can't say for sure that that's where the problem is.

  


  2. I also tested it on a macbook mini, with the same results.

  


  3. ffmpeg 6.1.1, MacOs 14.5

  


  4. Input filter arguments : time_base=1/1000000:sample_rate=48000:sample_fmt=1:channel_layout=stereo

  


  5. Output filter arguments : setpts=PTS-STARTPTS,aresample=48000:async=1:out_sample_fmt=8:out_chlayout=stereo,asetnsamples=n=1024

  


  


• HEVC with alpha [closed]

  3 mai 2024, par foxhable

  I trying create HEVC with alpha video from png images through ffmpeg.

  


  When i try, it outputs a video that works, has a transparent background and opens in QuickTime, but does not open in Safari. Then i try creating in prores 4444 codec and convert from macOS Context Menu -> Encode Selected Video Files with HEVC 1080p and Preserve Transparency. It has work - video with transparent background, open in QuickTime and in Safari.

  


  So i tried understand what a difference in meta data and only what i find its working video has HVEC encoder, but not working has Lavc61.5.103 hevc_videotoolbox. Can i somehow programmatically or from utilities like ffmpeg create video with HEVC With alpha, which working like from macOS context menu ? macOS context menu doesnt fit because i cant compress or create many videos

  


  Detail info

  


  I have example of working video. Info from ffprobe

  


  ffprobe movie-hevc.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\movie-hevc.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2021-01-02T10:33:38.000000Z
  Duration: 00:00:09.02, start: 0.000000, bitrate: 4053 kb/s
  Stream #0:0[0x1](und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, progressive), 1280x720 [SAR 1:1 DAR 16:9], 4046 kb/s, 60 fps, 60 tbr, 600 tbn (default)
      Metadata:
        creation_time   : 2021-01-02T10:33:38.000000Z
        handler_name    : Core Media Video
        vendor_id       : [0][0][0][0]
        encoder         : HEVC


  


  Info about video which i create in prores by ffmpeg command, then convert through macOS context menu

  


  command :

  


  ffmpeg -i a%d.png -r 30 -c:v prores_ks -profile:v 4  -allow_sw 1 -alpha_quality 1 -vtag hvc1 prores.mov


  


  info after converting

  


  ffprobe .\native-hevc.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\native-hevc.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2024-05-03T07:04:26.000000Z
  Duration: 00:00:12.77, start: 0.000000, bitrate: 8796 kb/s
  Stream #0:0[0x1](und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709), 1920x1920, 8792 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
      Metadata:
        creation_time   : 2024-05-03T07:04:27.000000Z
        handler_name    : Core Media Video
        vendor_id       : [0][0][0][0]
        encoder         : HEVC


  


  Info about video which i`m create direct in hevc by ffmpeg command

  


  ffmpeg -i a%d.png -r 30 -c:v hevc_videotoolbox -allow_sw 1 -alpha_quality 1 -vtag hvc1 ffmpeg-hevc.mov


  


  Info :

  


  ffprobe .\ffmpeg-hevc.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\ffmpeg-hevc.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    encoder         : Lavf61.3.103
  Duration: 00:00:12.77, start: 0.000000, bitrate: 3437 kb/s
  Stream #0:0[0x1]: Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bottom coded first (swapped)), 1920x1920, 3435 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
      Metadata:
        handler_name    : VideoHandler
        vendor_id       : FFMP
        encoder         : Lavc61.5.103 hevc_videotoolbox


  


  also i tried :

  


  

  • props -allow_sw 0 - get error

  


  • -alpha-quality 0.75, -pix_fmt bgra - safari not open, QT yes, transparent bg

  


  • without -vtag hvc1 - QuickTime cannot open

  


  • Tried convert from webm to hevc_videotoolbox - safari not open, QT yes, transparent bg

  


  • tried convert webm into pngs and in hevc_videotoolbox - safari not open, QT yes, transparent bg

  


  


  Tried answers :

  


  

  • https://stackoverflow.com/a/61663438

  


  • https://stackoverflow.com/a/69262399/17330336

  


  


  mac info :

  


  

  • macOS Monterey 12.7.2

  


  • Mac mini (Late 2012)

  


  • Core i5 3210M

  


  • Graphics Intel HD 4000

  


  


• Convert png images to HEVC with alpha video via ffmpeg [closed]

  6 mai 2024, par foxhable

  I am trying to create a video from a sequence of png images in the HEVC with alpha codec via ffmpeg.

  


  After the command

  


  ffmpeg -i a%d.png -r 30 -c:v hevc_videotoolbox -allow_sw 1 -alpha_quality 1 -vtag hvc1 ffmpeg-hevc.mov


  


  I get a video with a transparent background that opens in QuickTime, but not Safari.

  


  Info about this video via ffprobe :

  


  ffprobe .\ffmpeg-hevc.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\ffmpeg-hevc.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 512
    compatible_brands: qt
    encoder         : Lavf61.3.103
  Duration: 00:00:12.77, start: 0.000000, bitrate: 3437 kb/s
  Stream #0:0[0x1]: Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bottom coded first (swapped)), 1920x1920, 3435 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
      Metadata:
        handler_name    : VideoHandler
        vendor_id       : FFMP
        encoder         : Lavc61.5.103 hevc_videotoolbox


  


  I compared this to a video that has a transparent background and works in Safari and QuickTime

  


  ffprobe movie-hevc.mov
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '.\movie-hevc.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2021-01-02T10:33:38.000000Z
  Duration: 00:00:09.02, start: 0.000000, bitrate: 4053 kb/s
  Stream #0:0[0x1](und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, progressive), 1280x720 [SAR 1:1 DAR 16:9], 4046 kb/s, 60 fps, 60 tbr, 600 tbn (default)
      Metadata:
        creation_time   : 2021-01-02T10:33:38.000000Z
        handler_name    : Core Media Video
        vendor_id       : [0][0][0][0]
        encoder         : HEVC


  


  The only thing I noticed is the encoder. In the working version this is HEVC but in my Lavc61.5.103 hevc_videotoolbox.

  


  The question is, is it possible to create a video with a native HEVC codec via ffmpeg ?

  


  Tried answers :

  


  

  • https://stackoverflow.com/a/61663438

  


  • https://stackoverflow.com/a/69262399/17330336

  


  


  PC info :

  


  

  • macOS Monterey 12.7.2

  


  • Mac mini (Late 2012)

  


  • Core i5 3210M

  


  • Graphics Intel HD 4000