[kdenlive] defect audio rendering after project migration

[Chris]

Hi there,

I have filed a bug on the same or a similar issue:
https://bugs.kde.org/show_bug.cgi?id=361604

(Part of) the root cause could be that the conversion from previous 
levels 0-300 to db's is not correct. In the code I saw that it's done 
with natural logarithms (log) but I thought that decimal logarithms 
would have to be used (log10).

Best regards,
Chris

-----Original Message-----
From: Karl Kiniger
Sent:  Dienstag, April 12, 2016 18:58 +0200
To: Kdenlive
Subject: [kdenlive] defect audio rendering after project migration

> Hello again,
>
> using the following simple procedure the migration problem can be seen
> easily:
>
> 1. generate or take some audio, I took 20 seconds of C-major chord 
> from ffmpeg
>     (a newer version needed, I used current git), vibrato for better
>     listening experience...:
>
> ffmpeg  -f lavfi -i "sine=frequency=262:sample_rate=48000:duration=20" \
>          -f lavfi -i "sine=frequency=392:sample_rate=48000:duration=20" \
>          -f lavfi -i "sine=frequency=330:sample_rate=48000:duration=20" \
>          -f lavfi -i "sine=frequency=524:sample_rate=48000:duration=20" \
>          -filter_complex 
> "[0][1][2][3]amerge=inputs=4,pan=1c|c0=c0+c1+c2+c3,vibrato=d=0.2,volume=6dB[aout]" 
> \
>          -map "[aout]" -ac 1 \
>          -c:a pcm_s16le -y  audio.wav
>
> (you can also use any other audio source but now I understand ffmpeg
> filter_graph a little more :-)
>
>
> 2. create a new kdenlive-0.9.10 project and place audio.wav at the
>     beginning of an audio track
>
> 3. add volume(keyframeable) effect to the audio track, then adjust
>     start volume to 0 and volume at end of clip to 100
>
> 4. using X (cut) tool, cut the clip into three thirds.
>     (I took 3 parts because I wanted to see the ending volume of the
>     middle clip)
>
> 4a move the first and third part to another audio track keeping the 
> time position
>     (perhaps not even needed but I am in a hurry now:-)
>
> 5. save the project and import it into kdenlive-16.04, then render it
>
> Result: the linear increasing gain is not preserved properly. The
>          first part starts from volume zero but the following parts
>          dont continue the continous volume increase.
>
> Kdenlive-0.9.10 renders it without an audible glitch, the volume is
>          constantly increasing as intended.
>
> Greetings,
> Karl
>
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