[FFmpeg-user] Download audio only bytes with ffmpeg

[Tom Evans]

On Thu, Oct 24, 2013 at 5:42 PM, Feras Salim <feribg at gmail.com> wrote:
> Hi,
> I noticed a few youtube downloaders out there give the option of
> downloading only the audio and skipping the video stream. I was wondering
> if that is possible with ffmpeg.

Yes

> Given we have an url that has flv or mp4
> source and is seekable, is it possible to download only the audio form it
> and convert to mp3, without having to download the whole file first.

No. Audio and video packets are typically interweaved with each other,
to split out the audio you need to demux the entire file. The "youtube
downloaders" are also downloading the whole file.

> I tried the following commands but all of them resulted in using the
> bandwidth to download the entire video:
>
> ffmpeg -i "url" output.mp3
> ffmpeg -i "url" -vn -c:a copy output.mp3
> ffmpeg –i video.flv –vn –c:a libaac –ar 44100 –ac 2 –ab 64k audio.mp3
> ffmpeg -i video.flv -ab 160k -ac 2 -ar 44100 -vn audio.mp3
> ffmpeg -i “input” -vn -acodec copy output.mp3
> ffmpeg -i "input" -vn out.mp3
>
> Is doing something like that even possible?
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