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pcm/PcmDop: round down to the nearest multiple of 4 DSD bytes

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There was a discrepancy between what was written to the buffer and the
size returned by pcm_dsd_to_dop(): the "for" loop uses num_frames/2,
rounding down, while the return value is num_samples which is
num_frames*channels, without rounding.  This could cause undefined
data at the end of the destination buffer if the source buffer size
was not aligned to multiples of 8 bytes (4 DSD bytes per channel).

The latter however can occur in the 0.21 branch after commit
a06bf388d9

Closes #233
This commit is contained in:
Max Kellermann 2018-03-15 20:02:00 +01:00
parent 37b07a5e7c
commit a2340c313f
1 changed files with 4 additions and 3 deletions
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7
src/pcm/PcmDop.cxx
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@ -49,16 +49,17 @@ pcm_dsd_to_dop(PcmBuffer &buffer, unsigned channels,
const size_t num_src_samples = _src.size;
const size_t num_src_frames = num_src_samples / channels;
/* this rounds down and discards the last odd frame; not
/* this rounds down and discards up to 3 odd frames; not
elegant, but good enough for now */
const size_t num_frames = num_src_frames / 2;
const size_t num_dop_quads = num_src_frames / 4;
const size_t num_frames = num_dop_quads * 2;
const size_t num_samples = num_frames * channels;
uint32_t *const dest0 = (uint32_t *)buffer.GetT<uint32_t>(num_samples),
*dest = dest0;
auto src = _src.data;
for (size_t i = num_frames / 2; i > 0; --i) {
for (size_t i = num_dop_quads; i > 0; --i) {
for (unsigned c = channels; c > 0; --c) {
/* each 24 bit sample has 16 DSD sample bits
plus the magic 0x05 marker */