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Streamlined WavPack decoder by utilizing dsp functionality where it was

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applicable (like mono conversion and clipping) and eliminating the
conversion to 16-bit samples (everything is now returned as 28-bit).
This reduced boost ratio (on iRiver) by about 7% on those tracks that
require it.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8598 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Dave Bryant 2006-02-06 07:40:35 +00:00
parent f17e35d27b
commit ff40af42ba
2 changed files with 22 additions and 110 deletions
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56
apps/codecs/libwavpack/unpack.c
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@ -675,11 +675,17 @@ static void decorr_mono_pass (struct decorr_pass *dpp, long *buffer, long sample
// it is clipped and shifted in a single operation. Otherwise, if it's
// lossless then the last step is to apply the final shift (if any).
// This function has been modified for RockBox to return all integer samples
// as 28-bits, and clipping (for lossy mode) has been eliminated because this
// now happens in the dsp module.
static void fixup_samples (WavpackStream *wps, long *buffer, ulong sample_count)
{
ulong flags = wps->wphdr.flags;
int shift = (flags & SHIFT_MASK) >> SHIFT_LSB;
shift += 20 - (flags & BYTES_STORED) * 8; // this provides RockBox with 28-bit data
if (flags & FLOAT_DATA) {
float_values (wps, buffer, (flags & MONO_FLAG) ? sample_count : sample_count * 2);
return;
@ -689,7 +695,6 @@ static void fixup_samples (WavpackStream *wps, long *buffer, ulong sample_count)
ulong count = (flags & MONO_FLAG) ? sample_count : sample_count * 2;
int sent_bits = wps->int32_sent_bits, zeros = wps->int32_zeros;
int ones = wps->int32_ones, dups = wps->int32_dups;
// ulong mask = (1 << sent_bits) - 1;
long *dptr = buffer;
if (!(flags & HYBRID_FLAG) && !sent_bits && (zeros + ones + dups))
@ -707,51 +712,22 @@ static void fixup_samples (WavpackStream *wps, long *buffer, ulong sample_count)
shift += zeros + sent_bits + ones + dups;
}
if (flags & HYBRID_FLAG) {
long min_value, max_value, min_shifted, max_shifted;
switch (flags & BYTES_STORED) {
case 0:
min_shifted = (min_value = -128 >> shift) << shift;
max_shifted = (max_value = 127 >> shift) << shift;
break;
case 1:
min_shifted = (min_value = -32768 >> shift) << shift;
max_shifted = (max_value = 32767 >> shift) << shift;
break;
case 2:
min_shifted = (min_value = -8388608 >> shift) << shift;
max_shifted = (max_value = 8388607 >> shift) << shift;
break;
case 3:
default:
min_shifted = (min_value = (long) 0x80000000 >> shift) << shift;
max_shifted = (max_value = (long) 0x7FFFFFFF >> shift) << shift;
break;
}
if (!(flags & MONO_FLAG))
sample_count *= 2;
while (sample_count--) {
if (*buffer < min_value)
*buffer++ = min_shifted;
else if (*buffer > max_value)
*buffer++ = max_shifted;
else
*buffer++ <<= shift;
}
}
else if (shift) {
if (shift > 0) {
if (!(flags & MONO_FLAG))
sample_count *= 2;
while (sample_count--)
*buffer++ <<= shift;
}
else if (shift < 0) {
shift = -shift;
if (!(flags & MONO_FLAG))
sample_count *= 2;
while (sample_count--)
*buffer++ >>= shift;
}
}
// This function checks the crc value(s) for an unpacked block, returning the