On Mon, 22 Dec 2014 16:50:57 +0100 Lars Kiesow <lkie...@uos.de> wrote:
> Hi everyone, > I'm an FFmpeg user for quite a while now and though I might as well > switch to dev at some point... > > Please find attached to this mail a simple audio filter which makes it > possible to extract and print volume information from audio streams. It > works more or less like the showinfo filters only that it returns the > pcm value information for each audio sample. > > This output can then be used to easily plot a waveform image like this: > http://larskiesow.de/waveform.png > > > Example: > ./ffmpeg -nostats -i ... -filter:a aresample=100,showvolume -f null - > [...] > [Parsed_showvolume_1 @ 0x1bcc300] n: 0, channel: 0, volume: -239 > [Parsed_showvolume_1 @ 0x1bcc300] n: 1, channel: 0, volume: 126 > [Parsed_showvolume_1 @ 0x1bcc300] n: 2, channel: 0, volume: -74 > [Parsed_showvolume_1 @ 0x1bcc300] n: 3, channel: 0, volume: 29 > [...] > > Example (Generate waveform using gnuplot): > ./ffmpeg -nostats -i ... -ac 1 -filter:a aresample=100,showvolume \ > -f null - 2>&1 | grep '^\[Parsed_showvolume_1' | \ > gnuplot -p -e 'plot "-" using 9 with lines' > > > The code can be found at > https://github.com/lkiesow/FFmpeg/tree/libavfilter-audio-showvolume > and is also attached to this mail split into three separate patches. > > The first patch contains the filter itself, the necessary changes to > allfilters.c and the build files. The second patch contains the > documentation. Finally, the third patch contains a small script added > to the tools section utilizing the showvolume filter for generating > waveform images with gnuplot. > > Please let me know if you think it makes sense to add this code to > ffmpeg and/or if anything is still missing. > > Regards, > Lars So it just dumps each sample to the terminal? Wouldn't it be better to let gnu plot or whatever directly read data from a raw file (which the raw encoder/muxer could produce)? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
