Re: [FFmpeg-user] Why do these blank spots appear in spectrograms of converted youtube videos?
On Mon, Jan 09, 2017 at 09:51:34 +0800, Ethan Lewis wrote: > Thanks for suggestion but I do not have access to original audio as I > did not upload the videos myself. Well, you originally wrote: > I am confused why this is happening. Is it because of ffmpeg > conversion of m4a audio OR was it somehow fault of the original > recording? and it remained unclear whether you analyzed the downloaded /path/to/download/m4a/audio or the converted test1.wav - it seemed as if the latter, so it would make sense to analyze the former to rule out any modification by ffmpeg. (It also remained unclear - to me - which tool you used to create the spectrum you shared.) It would also make sense to take another known audio speech sample of your choice and see whether ffmpeg changes that. By the way, when I listen to that first YouTube clip, it has obvious heavy artefacts. I'm sure if that happens (on the "original" encoding side), that such side effects as spectrum holes can also occur. The heavier the compression, the more information which may be useless to the ear is omitted - that's how the psychoacoustics of these codecs work. (But I'm still just guessing as to where these holes *actually* come from. I'm also pretty sure a decoder such as ffmpeg AAC/MPEG4 audio decoder would not introduce holes which were not in the source.) Moritz ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Why do these blank spots appear in spectrograms of converted youtube videos?
> > > Have you compared with original audio? prior to resampling with ffmpeg? > > Thanks for suggestion but I do not have access to original audio as I did not upload the videos myself. ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
Re: [FFmpeg-user] Why do these blank spots appear in spectrograms of converted youtube videos?
On 1/6/17, Ethan Lewis wrote: > Hello > > I was converting a bunch of youtube videos into 16kHz wav files using ffmpeg > > I used the following commands > > youtube-dl -f best /path/to/youtube/video/ -f 'bestvideo,bestaudio' -o > '%(title)s.f%(format_id)s.%(ext)s' > > ffmpeg -i /path/to/download/m4a/audio -acodec pcm_s16le -ar 16000 -ac > test1.wav > > When I use these youtube videos > > https://www.youtube.com/watch?v=E1mGPeLqg2g > https://www.youtube.com/watch?v=XBFOP_pF7PY > > I see many blank spots in their spectrograms (see the ones uploaded here > https://drive.google.com/file/d/0BzNdoGke8tyRSGgwUUtSTkgxdEE/view?usp=sharing > ) > > Natural speech should not have such artefacts. > > I am confused why this is happening. Is it because of ffmpeg conversion of > m4a audio OR was it somehow fault of the original recording? Have you compared with original audio? prior to resampling with ffmpeg? ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
[FFmpeg-user] Why do these blank spots appear in spectrograms of converted youtube videos?
Hello I was converting a bunch of youtube videos into 16kHz wav files using ffmpeg I used the following commands youtube-dl -f best /path/to/youtube/video/ -f 'bestvideo,bestaudio' -o '%(title)s.f%(format_id)s.%(ext)s' ffmpeg -i /path/to/download/m4a/audio -acodec pcm_s16le -ar 16000 -ac test1.wav When I use these youtube videos https://www.youtube.com/watch?v=E1mGPeLqg2g https://www.youtube.com/watch?v=XBFOP_pF7PY I see many blank spots in their spectrograms (see the ones uploaded here https://drive.google.com/file/d/0BzNdoGke8tyRSGgwUUtSTkgxdEE/view?usp=sharing ) Natural speech should not have such artefacts. I am confused why this is happening. Is it because of ffmpeg conversion of m4a audio OR was it somehow fault of the original recording? Thanks. ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".