[FFmpeg-devel] af_silencedetect.c: silencedetect reporting format change to follow blackdetect reporting format

Dave Rice dave at dericed.com
Tue May 20 01:11:47 CEST 2014

On May 19, 2014, at 6:52 PM, Billy Shambrook <billy.shambrook at gmail.com> wrote:

> On Sun, May 18, 2014 at 11:39:57PM +0100, Billy Shambrook wrote:
>>> https://github.com/FFmpeg/FFmpeg/pull/68
>>> Reports silence using the same format as the vf blackdetect. This is to
>>> simplify parsing the output of each filter.
>> This delays the silence_start printing. It can be an issue for real time.
>> The main motivation behind this filter was originally to detect a silence
>> issue in live stream. This is why it is important to print the
>> silence_start ASAP.
>> BTW, you're not supposed to parse that output, metadata injections are
>> here for that (use ffprobe). But since some people might be doing this
>> anyway, you should probably bump micro version in libavfilter/version.h.
> Thanks for the info. I have updated my pull request with the version bumped.
> I have read into metadata injections and looks extremely promising since I
> use ffprobe as well to query my assets. I have seen that blackdetect
> currently does use metadata injections, but will try to get a patch out for
> that to share.
> One question is that I have managed to get the two commands below to work
> to utilise metadata injection (blackdetect doesn't yet), however, is there
> a way to combine these into one command?
> ffprobe -f lavfi -i movie=1080p24.mxf,b
> ​lackdetect​
> -show_frames -of json
> ffprobe -f lavfi -i amovie=1080p24.mxf,silencedetect -show_frames -of json

Not tested but try:
ffprobe -f lavfi -i movie=1080p24.mxf,b​lackdetect​[out0];amovie=1080p24.mxf,silencedetect[out1] -show_frames -of json
Dave Rice

More information about the ffmpeg-devel mailing list