MP4 to MP3 (Video+Audio -> Audio)

[Shevek]

On 25 August 2013 17:51, Kapitano <kapitano72 at gmail.com> wrote:
> On 8/25/2013 16:48 PM, Shevek wrote:
>>
>> After download, you can use ffmpeg to extract the audio
>>
>> ffmpeg -i file.mp4 -vn -acodec copy file.aac
>
>
> Can ffmpeg identify which audio and video codecs are used in a given file?
> Is there a way to 'ask' it whether an MP4 has sound encoded in aac. mp3,
> speex etc?

ffmepg -i file.mp4 will display the file's info, look for a line like this:

Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo,
fltp, 93 kb/s

Also, MediaInfo is very useful for this task