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[rgomez]

Hello,

I am playing with a waveform drawer and would like to have the RMS and peak level for the period in the same call. I am using BASS_ChannelGetLevelEx, but what I have to do now is have two (decoding) channels and process them in the same cycle. This effectively doubles the processing time, for what I can see... and of course, it makes sense. I am trying to avoid this...

I wonder then if there is a way to obtain this on the same call? I am working with lengthy audios (usually 24 hours long)  so the period I am using is not very fine: 660ms and 20 seconds

Thanks!

[Ian @ un4seen]

It isn't possible to get both levels in a single BASS_ChannelGetLevelEx call, but instead of using a separate decoder for each level, you could use a push stream for both: get data from the source, feed it to the push stream and get the peak level, feed it to the push stream again and get the RMS level.

Code SelectExpand

BASS_CHANNELINFO info;
BASS_ChannelGetInfo(decoder, &info); // get source info
levelstream = BASS_StreamCreate(info.freq, info.chans, info.flags | BASS_STEAM_DECODE, STREAMPROC_PUSH, 0); // create push stream with same format
...
got = BASS_ChannelGetData(decoder, buffer, bufsize); // get data from source
BASS_StreamPutData(levelstream, buffer, got); // feed data to the level stream
BASS_ChannelGetLevelEx(levelstream, &peaklevel, 1, BASS_LEVEL_MONO); // get the peak level
BASS_StreamPutData(levelstream, buffer, got); // feed data to the level stream again
BASS_ChannelGetLevelEx(levelstream, &rmslevel, 1, BASS_LEVEL_MONO | BASS_LEVEL_RMS); // get the RMS level

Make sure the BASS_ChannelGetLevelEx "length" parameter at least matches (or exceeds) the BASS_ChannelGetData "length" parameter, to avoid a build-up of data in the push stream.

[rgomez]

Thank you Ian!

[Ian @ un4seen]

The code above will work with both playback and decoding channels, but if you're only dealing with decoding channels, then another (possibly simpler) option is to use splitters, ie. a splitter for each level. Something like this:

Code SelectExpand

peakstream = BASS_Split_StreamCreate(decoder, BASS_STREAM_DECODE, NULL); // create splitter for peak levels
rmsstream = BASS_Split_StreamCreate(decoder, BASS_STREAM_DECODE | BASS_SPLIT_SLAVE, NULL); // create "slave" splitter for RMS levels
...
BASS_ChannelGetLevelEx(peakstream, &peaklevel, length, BASS_LEVEL_MONO); // get the peak level
BASS_ChannelGetLevelEx(rmsstream, &rmslevel, length, BASS_LEVEL_MONO | BASS_LEVEL_RMS); // get the RMS level

Note BASS_ChannelGetLevelEx needs to be called on the non-slave splitter (peakstream) first. Please see the BASS_Split_StreamCreate documentation for details.

[rgomez]

Hello Ian,

The original code is working fine. I wonder, using splitter streams, if I understand correctly, I would not need to call BASS_ChannelGetData first? It would be just the BASS_ChannelGetLevelEx calls on the two splitter streams, and that's it?

[Ian @ un4seen]

That's correct, there would be no need for you to call BASS_ChannelGetData. BASS_ChannelGetLevelEx itself uses BASS_ChannelGetData internally to get the data that it measures.

[rgomez]

Thank you Ian,

This solution is simpler code-wise and works great.