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audio/format: revise af_format_conversion_score

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* (de)planarize -1
* pad 1 byte -8
* truncate 1 byte -1024
* float -> int 1048576 * (8 - dst_bytes)
* int -> float -512

Now the score is negative if and only if the conversion is lossy
(e.g. previously s24 -> float was given a negative (lossy) score),
However, int->float is still considered bad
(s16->float is worse than than s16->s32).

This penalizes any loss of precision more than performance / bandwidth hits.
For example, previously s24->s16p was considered equal to s24->u8.

Finally, we penalize padding more than (de)planarizing as this will
increase the output size for example with ao_lavc.
This commit is contained in:
Kevin Mitchell 2015-09-10 20:52:04 -07:00
parent 269f271b73
commit b7144ad8bf
1 changed files with 13 additions and 8 deletions
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21
audio/format.c
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@ -190,20 +190,25 @@ static int af_format_conversion_score(int dst_format, int src_format)
if (af_fmt_is_float(dst_format) != af_fmt_is_float(src_format)) {
int dst_bytes = af_fmt_to_bytes(dst_format);
if (af_fmt_is_float(dst_format)) {
// For int->float, always prefer 32 bit float.
score -= dst_bytes == 4 ? 0 : 1;
// For int->float, consider a lower bound on the precision difference.
int bytes = (dst_bytes == 4 ? 3 : 6) - af_fmt_to_bytes(src_format);
if (bytes >= 0) {
score -= 8 * bytes; // excess precision
} else {
score += 1024 * (bytes - 1); // precision is lost (i.e. s32 -> float)
}
} else {
// For float->int, always prefer highest bit depth int
score -= 8 - dst_bytes;
// float->int is the worst case. Penalize heavily and
// prefer highest bit depth int.
score -= 1048576 * (8 - dst_bytes);
}
// Has to convert float<->int - Consider this the worst case.
score -= 2048;
score -= 512; // penalty for any float <-> int conversion
} else {
int bytes = af_fmt_to_bytes(dst_format) - af_fmt_to_bytes(src_format);
if (bytes > 0) {
score -= 1 + bytes; // has to add padding
score -= 8 * bytes; // has to add padding
} else if (bytes < 0) {
score -= 1024 - bytes; // has to reduce bit depth
score += 1024 * (bytes - 1); // has to reduce bit depth
}
}
return score;