'Twas brillig, and Tanu Kaskinen at 05/10/12 13:58 did gyre and gimble: > On Wed, 2012-10-03 at 08:50 +0200, David Henningsson wrote: >> On 10/02/2012 10:38 PM, Tanu Kaskinen wrote: >>> On Mon, 2012-10-01 at 17:06 +0200, David Henningsson wrote: >>>> If there is no silence memblock and no data, pa_memblockq_peek can >>>> return NULL. In this case, do not crash on an assertion in >>>> pa_memblock_acquire, but instead return a proper error to the client. >>> >>> If there is no data in the buffer, pa_stream_peek() is supposed to >>> return NULL according to the documentation. And it does that: if there's >>> no data, pa_memblock_peek() will return a negative value, causing >>> pa_stream_peek() to return NULL. >>> >>> The problem is the case where the buffer does contain data, but not at >>> the read index. That is, there is a hole in the buffer. The client >>> documentation doesn't have any warnings about holes, so the only safe >>> way to handle holes is to return silence. Fixing this should be a simple >>> matter of giving a silence memchunk when creating record_memblockq. >> >> I'm not so sure. Silence, as in all zeroes, might work for S16 audio >> data, but what about other formats? Compressed audio? Peak audio (which >> I think is the case here)? Etc. > > Good point. Regarding PCM, if pa_memchunk_silence() is used, the > function will take care of filling the memory with appropriate content. > But that doesn't work with compressed audio. > >> Also maybe it could also be valuable for the client to distinguish >> between no data available, and valid zero data. >> >> How about returning NULL and adding to the documentation something like: >> >> -If no data is available this will return a NULL pointer. >> +If no data is available (at the current read position), this will >> return a NULL pointer. > > An addition: the client probably wants to know how large the hole is. It > might be possible to figure that out somehow from the read index, but I > think it would make sense to return the hole size in the length > parameter. This discussion seemed to stagnate. Is this worth fixing/documenting for the 3.0 release? Col -- Colin Guthrie gmane(at)colin.guthr.ie http://colin.guthr.ie/ Day Job: Tribalogic Limited http://www.tribalogic.net/ Open Source: Mageia Contributor http://www.mageia.org/ PulseAudio Hacker http://www.pulseaudio.org/ Trac Hacker http://trac.edgewall.org/
