ref: ffe6801b3990fbe1fab930c19afd7f1582aa9c5c
parent: 3ee08beb133a2ac7d239f5f89c7651eb617517c9
author: Ulrich Klauer <ulrich@chirlu.de>
date: Fri Jan 6 18:06:54 EST 2012
alsa: make select_format() extensible Rewrite select_format() of the ALSA format handler to be (less concise, but) more readable and extensible. Specifically, allow more formats than exactly one signed-int/unsigned-int pair per sample size, and sample sizes that are not divisible by 8.
--- a/src/alsa.c
+++ b/src/alsa.c
@@ -1,4 +1,4 @@
-/* libSoX device driver: ALSA (c) 2006-9 SoX contributors
+/* libSoX device driver: ALSA (c) 2006-2012 SoX contributors
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
@@ -22,51 +22,79 @@
snd_pcm_uframes_t buf_len, period;
snd_pcm_t * pcm;
char * buf;
- int format;
+ unsigned int format;
} priv_t;
-#define NBYTES bytes_size[(ft->encoding.bits_per_sample >> 3) - 1]
-#define NSIZES array_length(bytes_size)
+static const
+ struct {+ unsigned int bits;
+ enum _snd_pcm_format alsa_fmt;
+ unsigned int bytes; /* occupied in the buffer per sample */
+ sox_encoding_t enc;
+ } formats[] = {+ /* order by # of bits; within that, preferred first */
+ { 8, SND_PCM_FORMAT_S8, 1, SOX_ENCODING_SIGN2 },+ { 8, SND_PCM_FORMAT_U8, 1, SOX_ENCODING_UNSIGNED },+ { 16, SND_PCM_FORMAT_S16, 2, SOX_ENCODING_SIGN2 },+ { 16, SND_PCM_FORMAT_U16, 2, SOX_ENCODING_UNSIGNED },+ { 24, SND_PCM_FORMAT_S24, 4, SOX_ENCODING_SIGN2 },+ { 24, SND_PCM_FORMAT_U24, 4, SOX_ENCODING_UNSIGNED },+ { 32, SND_PCM_FORMAT_S32, 4, SOX_ENCODING_SIGN2 },+ { 32, SND_PCM_FORMAT_U32, 4, SOX_ENCODING_UNSIGNED },+ { 0, 0, 0, SOX_ENCODING_UNKNOWN } /* end of list */+ };
-static const int bytes_size[] = {1, 2, 4, 4}, formats[][NSIZES] = {- {SND_PCM_FORMAT_S8, SND_PCM_FORMAT_S16, SND_PCM_FORMAT_S24,- SND_PCM_FORMAT_S32},
- {SND_PCM_FORMAT_U8, SND_PCM_FORMAT_U16, SND_PCM_FORMAT_U24,- SND_PCM_FORMAT_U32}};
-
static int select_format(
sox_encoding_t * encoding_,
unsigned * nbits_,
snd_pcm_format_mask_t const * mask,
- int * format)
+ unsigned int * format)
{- unsigned can_do[NSIZES], i, j, index = (*nbits_ >> 3) - 1, nbits;
- sox_encoding_t encoding = *encoding_;
+ unsigned int from = 0, to; /* NB: "to" actually points one after the last */
+ int cand = -1;
- for (i = 0; i < NSIZES; ++i) for (can_do[i] = 0, j = 0; j < 2; ++j)
- can_do[i] |= snd_pcm_format_mask_test(mask, formats[j][i]);
+ while (formats[from].bits < *nbits_ && formats[from].bits != 0)
+ from++; /* find the first entry with at least *nbits_ bits */
+ for (to = from; formats[to].bits != 0; to++) ; /* find end of list */
- if (index >= NSIZES ||
- (encoding != SOX_ENCODING_SIGN2 && encoding != SOX_ENCODING_UNSIGNED)){- encoding = SOX_ENCODING_SIGN2;
- index = 2;
+ while (to > 0) {+ unsigned int i, bits_next = 0;
+ for (i = from; i < to; i++) {+ lsx_debug_most("select_format: trying #%u", i);+ if (snd_pcm_format_mask_test(mask, formats[i].alsa_fmt)) {+ if (formats[i].enc == *encoding_) {+ cand = i;
+ break; /* found a match */
+ } else if (cand == -1) /* don't overwrite a candidate that
+ was earlier in the list */
+ cand = i; /* will work, but encoding differs */
+ }
+ }
+ if (cand != -1)
+ break;
+ /* no candidate found yet; now try formats with less bits: */
+ to = from;
+ if (from > 0)
+ bits_next = formats[from-1].bits;
+ while (from && formats[from-1].bits == bits_next)
+ from--; /* go back to the first entry with bits_next bits */
}
- while (!can_do[index]) if (++index == NSIZES) /* Search up */
- for (--index; !can_do[index];) if (--index >= NSIZES) /* then down */
- return -1;
- nbits = (index + 1) << 3;
- if (encoding == SOX_ENCODING_SIGN2 &&
- !snd_pcm_format_mask_test(mask, formats[0][index]))
- encoding = SOX_ENCODING_UNSIGNED;
+ if (cand == -1) {+ lsx_debug("select_format: no suitable ALSA format found");+ return -1;
+ }
- if (*nbits_ != nbits || *encoding_ != encoding) {+ if (*nbits_ != formats[cand].bits || *encoding_ != formats[cand].enc) { lsx_warn("can't encode %u-bit %s", *nbits_,sox_encodings_info[*encoding_].desc);
- *nbits_ = nbits;
- *encoding_ = encoding;
+ *nbits_ = formats[cand].bits;
+ *encoding_ = formats[cand].enc;
}
- *format = formats[encoding == SOX_ENCODING_UNSIGNED][index];
+ lsx_debug("selecting format %d: %s (%s)", cand,+ snd_pcm_format_name(formats[cand].alsa_fmt),
+ snd_pcm_format_description(formats[cand].alsa_fmt));
+ *format = cand;
return 0;
}
@@ -91,7 +119,7 @@
_(snd_pcm_format_mask_malloc, (&mask)); /* Set format: */
snd_pcm_hw_params_get_format_mask(params, mask);
_(select_format, (&ft->encoding.encoding, &ft->encoding.bits_per_sample, mask, &p->format));
- _(snd_pcm_hw_params_set_format, (p->pcm, params, p->format));
+ _(snd_pcm_hw_params_set_format, (p->pcm, params, formats[p->format].alsa_fmt));
snd_pcm_format_mask_free(mask), mask = NULL;
n = ft->signal.rate; /* Set rate: */
@@ -109,7 +137,8 @@
snd_strerror(err));
/* Set buf_len > > sox_globals.bufsiz for no underrun: */
- p->buf_len = sox_globals.bufsiz * 8 / NBYTES / ft->signal.channels;
+ p->buf_len = sox_globals.bufsiz * 8 / formats[p->format].bytes /
+ ft->signal.channels;
_(snd_pcm_hw_params_get_buffer_size_min, (params, &min));
_(snd_pcm_hw_params_get_buffer_size_max, (params, &max));
p->period = range_limit(p->buf_len, min, max) / 8;
@@ -125,7 +154,7 @@
snd_pcm_hw_params_free(params), params = NULL;
_(snd_pcm_prepare, (p->pcm));
p->buf_len *= ft->signal.channels; /* No longer in `frames' */
- p->buf = lsx_malloc(p->buf_len * NBYTES);
+ p->buf = lsx_malloc(p->buf_len * formats[p->format].bytes);
return SOX_SUCCESS;
error:
@@ -164,7 +193,7 @@
} while (n <= 0);
i = n *= ft->signal.channels;
- switch (p->format) {+ switch (formats[p->format].alsa_fmt) { case SND_PCM_FORMAT_S8: {int8_t * buf1 = (int8_t *)p->buf;
while (i--) *buf++ = SOX_SIGNED_8BIT_TO_SAMPLE(*buf1++,);
@@ -211,7 +240,7 @@
while (i--) *buf++ = SOX_UNSIGNED_32BIT_TO_SAMPLE(*buf1++,);
break;
}
- default: lsx_fail_errno(ft, SOX_EFMT, "invalid format");
+ default: lsx_fail_errno(ft, SOX_EFMT, "invalid format");
return 0;
}
}
@@ -227,7 +256,7 @@
for (done = 0; done < len; done += n) {i = n = min(len - done, p->buf_len);
- switch (p->format) {+ switch (formats[p->format].alsa_fmt) { case SND_PCM_FORMAT_S8: {int8_t * buf1 = (int8_t *)p->buf;
while (i--) *buf1++ = SOX_SAMPLE_TO_SIGNED_8BIT(*buf++, ft->clips);
@@ -274,10 +303,13 @@
while (i--) *buf1++ = SOX_SAMPLE_TO_UNSIGNED_32BIT(*buf++, ft->clips);
break;
}
+ default: lsx_fail_errno(ft, SOX_EFMT, "invalid format");
+ return 0;
}
for (i = 0; i < n; i += actual * ft->signal.channels) do {- actual = snd_pcm_writei(
- p->pcm, p->buf + i * NBYTES, (n - i) / ft->signal.channels);
+ actual = snd_pcm_writei(p->pcm,
+ p->buf + i * formats[p->format].bytes,
+ (n - i) / ft->signal.channels);
if (errno == EAGAIN) /* Happens naturally; don't report it: */
errno = 0;
if (actual < 0 && recover(ft, p->pcm, (int)actual) < 0)