On Sun, 2013-07-21 at 23:14 +0200, Peter Meerwald wrote: > Hello, > > the patch series aims to resubmit a patch to reorder the resampling > pipeline; it former patch was dropped due to issues with leftover data > handling; patch 11 has more details > > the resampling pipeline is > conv -> remap -> resample -> conv > > patch 11 introduces the following, alternative pipeline > conv -> resample -> remap -> conv > when the number of input channels is less than the number of output channels > > the resample stage may not consume all data passed; hence the leftover > data has to be stored; the data is presented again to the resample stage > together with the next input data > > the strategy for the fix is to allow reinserting leftover data not only > in the remap stage, but also in the conv(to work format) stage; i.e. the > stage run before the resampler in case of the alternative pipeline > > patches 1 and 2 introduce helper variables work_channels and w_fz > representing the number of channels and the byte per frame, respectively, > in the resample stage > > patch 3 makes the impl_resample() function return the number of leftover > frames (to make leftover handling more visible in the code) > > patch 4 move leftover handling from impl_resample() to resample() > > patch 5 and 6 is cleanup and introduces a helper function fit_buf() for > buffer allocation > > patch 7 introduces a pointer to the output buffer of the stage run before > the resamplers > > patch 8 is cleanup > > patch 9 extends fit_buf() so that it can copy leftover data when allocating > a new buffer > > patch 10 adds leftover data handling to the convert_to_work_format() > function > > patch 11 finally enables the two different pipelines; the patch is important > e.g. when a mono channel is remapped and resampled to quad-channel -- it > saves resampling 75% of the data! > > > > I also considered moving the leftover handling into impl_resample(), but > this leads to more code duplication and buffer copying; new API to find the amount > of leftover data store in the resamplers might be needed as well > > thanks to the cleanups preceding patch 11, the complexity of the more flexible > pipeline keeps managable I have rebased and reviewed patches 1-5, and all looked good, so pushed. I'll continue the review later (hopefully today). -- Tanu
