Bug#775983: oggenc: Invalid memory access with low sampling rate

Martin Steghöfer martin at steghoefer.eu
Thu Oct 8 21:40:17 UTC 2015


tags 775983 + confirmed
retitle 775983 oggenc: Invalid memory access with low sampling rate
thanks


The problem seems to be independent of oggenc's resampler. It can be observed with any input file having a low sampling rate, e.g.:

> dd if=/dev/zero bs=1024 count=1000 | valgrind oggenc -r -R 500 - > /dev/null

The cut-off frequency seems to be 512 Hz. Everything >= 512 Hz works, everything < 512 Hz exposes the invalid memory access.

To me it looks a little bit like libvorbis cannot encode audio with such a low sampling rate. But either it fails to refuse such inputs with a sanity check, or oggenc doesn't properly check the return codes. However, I've checked the oggenc encoder code and it seems to be pretty thorough about return code checking, both in generally and specifically regarding the calls to the functions "vorbis_encode_setup_managed" and "vorbis_encode_setup_managed", which is where the sampling rate is passed to libvorbis.

Looks like this needs some proper debugging...

Cheers,
Martin



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