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• How to modify pitch in audio of video file with singing voices

  9 janvier 2020, par Keith Bennett

  I have some karaoke .mp4 video files (legally obtained) for Thai songs, and want to convert the pitch downward to fit my singing range. I’ve gotten most of the way there thanks to https://superuser.com/questions/292833/how-to-change-audio-frequency/1076762#1076762
  using a command line like this :

  ffmpeg -i in.mp4 -af 'asetrate=35280.0,atempo=1.25' out.mp4

  ...but the human singing voices don’t sound natural at the modified pitch.

  Is there a better way to change the pitch ? I know some commercial products can do this.

  By the way, I wrote a Ruby script to simplify this ffmpeg call ; it’s at https://gist.github.com/keithrbennett/9ba7043792bfb2fcc92d615076a8413f. It enables you to specify a single factor, and modifies both pitch and tempo accordingly.

• Is FFmpegAudioDecoder supposed to reinitialize upon append of new init segment

  14 novembre 2023, par martin

  I am attempting to switch audio tracks but when switching the FFmpegAudioDecoder never reinitializes like it does with video tracks of differing resolutions. I am not certain if this is the intended behavior of FFmpegAudioDecoder and would love to learn more about the expected behavior.

  


  When switching audio tracks I end up calling the following operations :

  


  if sourceBuffer.getIsUpdate() {sourceBuffer.abort()}
sourceBuffer.remove(0-videoDuration)
initSegmentDataStream = fetch init segment of new audio representation
sourceBuffer.appendBuffer(initSegmentDataStream)


  


  These are the Media tab messages from initial video load

  


  ChunkDemuxer
Selected FFmpegAudioDecoder for audio decoding, config: codec: aac, profile: unknown, bytes_per_channel: 2, channel_layout: STEREO, channels: 2, samples_per_second: 48000, sample_format: Signed 16-bit, bytes_per_frame: 4, seek_preroll: 0us, codec_delay: 0, has extra data: false, encryption scheme: Unencrypted, discard decoder delay: false, target_output_channel_layout: STEREO, target_output_sample_format: Unknown sample format, has aac extra data: true
Cannot select DecryptingVideoDecoder for video decoding
Cannot select VDAVideoDecoder for video decoding
Cannot select VpxVideoDecoder for video decoding
Selected Dav1dVideoDecoder for video decoding, config: codec: av1, profile: av1 profile main, level: not available, alpha_mode: is_opaque, coded size: [1280,720], visible rect: [0,0,1280,720], natural size: [1280,720], has extra data: false, encryption scheme: Unencrypted, rotation: 0°, flipped: 0, color space: {primaries:BT709, transfer:BT709, matrix:BT709, range:LIMITED}
Dropping audio frame (DTS 0us PTS -105375us,-62709us) that is outside append window [0us,9223372036854775807us).
Dropping audio frame (DTS 42666us PTS -62708us,-20042us) that is outside append window [0us,9223372036854775807us).
Truncating audio buffer which overlaps append window start. PTS -20041us frame_end_timestamp 22625us append_window_start 0us
Effective playback rate changed from 0 to 1


  


  For comparison this is what I get when appending the init segment of a different video resolution / track

  


  video decoder config changed midstream, new config: codec: av1, profile: av1 profile main, level: not available, alpha_mode: is_opaque, coded size: [1920,1080], visible rect: [0,0,1920,1080], natural size: [1920,1080], has extra data: false, encryption scheme: Unencrypted, rotation: 0°, flipped: 0, color space: {primaries:BT709, transfer:BT709, matrix:BT709, range:LIMITED}



  


  Chrome version : Version 119.0.6045.123 (Official Build)

  


  When appending the new init segment of an audio track I was expecting the FFmpegAudioDecoder to be reinitialized like the Dav1dVideoDecoder does for video tracks

  


• FFmpeg : Encode x264 with AMD GPU on Windows ?

  20 septembre 2023, par ZeroTek

  I am currently trying to record a Video on my Lenovo Laptop with its Built-In Webcam using FFmpeg on Windows 10. One of my goals is to keep the CPU Usage as low as possible, that's why i want to push the h264 encoding to the GPU. 
Now it gets a bit tricky here with my Laptop. Because it uses two GPUs. The first GPU is a Intel HD 5500 Graphics Unit as Part of the CPU. This one is most likly used for non-demanding Applications like office etc. to save Energy. The other one is a AMD R5 M330 that will be used for graphic intense applications like gaming.

  



  Currently, i am using the following command to encode the Webcam Stream on the Intel HD GPU :

  



  ffmpeg -f dshow -vcodec mjpeg -video_size 1280x720 -framerate 30 video="Lenovo EasyCamera":audio="Mikrofon (Realtek High Definition Audio)" -c:v h264_qsv -g 60 -q 28 -look_ahead 0 -preset:v faster -c:a aac -q:a 0.6 -r 30 output.mp4


  



  This does work so far but it seems this GPU does not have enough Power to keep up with the framerate on higher bitrates or with a high amount of i-frames. The Video starts lacking and skipping frames. If i am using CPU encoding everything works smooth.

  



  Now that my Laptop got that second AMD GPU with a lot more Power it would be a nice Try to encode on that one, but i can't find any information about how to encode on AMD Hardware on Windows 10. So my question is : How does the ffmpeg command look like to use AMD Hardware for h264 encoding ?