[FFmpeg-user] ebuR128 display of live source

[Bouke / Videotoolshed]

> On 20 Mar 2023, at 11:59, Gyan Doshi <ffmpeg at gyani.pro> wrote:
> 
> 
> 
> On 2023-03-19 03:47 pm, Bouke / Videotoolshed wrote:
>> C:\Users\Bouke>ffmpeg.exe -nostats -f dshow -ar 48000 -i audio="Line (Steinberg CI2)" -filter_complex "ebur128=peak=true" -f null -
>> 
>> Now, this works fine, BUT, the output to stderr is at very irregular intervals.
>> Output is as expected lines like:
>> [Parsed_ebur128_0 @ 000001915fe77a40] t: 0.199979   TARGET:-23 LUFS    M:-120.7 S:-120.7     I: -70.0 LUFS       LRA:   0.0 LU  FTPK: -55.5 -71.0 dBFS  TPK: -55.2 -69.8 dBFS
>> [Parsed_ebur128_0 @ 000001915fe77a40] t: 0.299979   TARGET:-23 LUFS    M:-120.7 S:-120.7     I: -70.0 LUFS       LRA:   0.0 LU  FTPK: -56.2 -72.7 dBFS  TPK: -55.2 -69.8 dBFS
>> 
>> Now, sometimes one line is outputted (as expected) but most of the times it’s 2 up to 4 lines at the same time.
>> That does not make for a pretty visual show if I parse it ‘as fast as possible’
>> 
>> I could buffer the output and do my display stuff for each line with my own interval / if buffer line length >= 4 or alike, but that would introduce half a second delay, and that does not compute well in my brain when I have to ride the faders…
>> 
>> Is there anything I can do to have FFmpeg spit out each line ‘as soon as it is available’?
>> (I’m starting FFmpeg from Python, listening to StdOut / StdErr.)
> 
> The ebur filter has an option to store the readouts as frame metadata. You can then use ametadata filter to print out the metadata to a file or pipe. The filter has an option 'direct' to flush out writes immediately instead of buffering them.

Hi Gyan,
While searching how to do this I found something else (by your hand :-)

https://trac.ffmpeg.org/ticket/8559

Where you wrote:
>>Add -audio_buffer_size 10 after -f dshow and check.

I’m on Mac now and have to do other work, but it seemed to have helped the guy before me.
Thx,
Bouke


> Regards,
> Gyan
> 
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