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pcm_meter: let the s16 scope degrade instead of killing the caller #516

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pcm_meter: let the s16 scope degrade instead of killing the caller #516

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26 changes: 24 additions & 2 deletions src/pcm/pcm_meter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1005,6 +1005,7 @@ typedef struct _snd_pcm_scope_s16 {
snd_pcm_uframes_t old;
int16_t *buf;
snd_pcm_channel_area_t *buf_areas;
int silent;
} snd_pcm_scope_s16_t;

static int s16_enable(snd_pcm_scope_t *scope)
Expand Down Expand Up @@ -1043,15 +1044,31 @@ static int s16_enable(snd_pcm_scope_t *scope)
idx = snd_pcm_linear_convert_index(spcm->format, SND_PCM_FORMAT_S16);
break;
default:
return -EINVAL;
/* No S16 conversion exists for this format - DSD, the 3-byte
* packed formats, float. Leaving the scope disabled is worse
* than useless: scopes that depend on it, including our own
* level scope, call snd_pcm_scope_s16_get_channel_buffer()
* from their update callback and that assert()s on the buffer
* this function never allocated, killing the application.
* Hand out a silent buffer instead, so a scope reads zero on a
* format it cannot see rather than aborting the process.
*/
snd_error(PCM, "s16 scope: no S16 conversion for format %s, scopes will read silence",
snd_pcm_format_name(spcm->format));
s16->silent = 1;
idx = 0;
break;
}
s16->index = idx;
if (spcm->format == SND_PCM_FORMAT_IMA_ADPCM) {
s16->adpcm_states = calloc(spcm->channels, sizeof(*s16->adpcm_states));
if (!s16->adpcm_states)
return -ENOMEM;
}
s16->buf = malloc(meter->buf_size * 2 * spcm->channels);
/* calloc, not malloc: when s16->silent is set nothing ever writes to
* this buffer and scopes must read silence, not uninitialised memory.
*/
s16->buf = calloc(meter->buf_size * 2 * spcm->channels, 1);
if (!s16->buf) {
free(s16->adpcm_states);
return -ENOMEM;
Expand Down Expand Up @@ -1103,6 +1120,11 @@ static void s16_update(snd_pcm_scope_t *scope)
snd_pcm_t *spcm = meter->gen.slave;
snd_pcm_sframes_t size;
snd_pcm_uframes_t offset;
if (s16->silent) {
/* Nothing to convert; the buffer stays zero. */
s16->old = meter->now;
return;
}
size = meter->now - s16->old;
if (size < 0)
size += spcm->boundary;
Expand Down
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