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opusdec: Fix PLC frame size calculations

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Previously, PLC frames always had a length of 120ms, which caused audio
quality degradation and synchronization errors. Fix this by calculating an
appropriate length for the PLC frame.

The length must be a multiple of 2.5ms. Calculate a multiple of 2.5ms that
is nearest to the current PLC length. Any leftover PLC length that didn't
make it into this frame is accumulated for the next PLC frame.

https://bugzilla.gnome.org/show_bug.cgi?id=725167
This commit is contained in:
Carlos Rafael Giani 2015-04-20 15:04:56 +02:00 committed by Olivier Crête
parent b4fe1b516b
commit a595874aac
2 changed files with 51 additions and 4 deletions
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53
ext/opus/gstopusdec.c
View file

@ -157,6 +157,7 @@ gst_opus_dec_reset (GstOpusDec * dec)
dec->r128_gain = 0;
dec->sample_rate = 0;
dec->n_channels = 0;
dec->leftover_plc_duration = 0;
}
static void
@ -446,9 +447,53 @@ opus_dec_chain_parse_data (GstOpusDec * dec, GstBuffer * buffer)
size = 0;
}
/* use maximum size (120 ms) as the number of returned samples is
not constant over the stream. */
samples = 120 * dec->sample_rate / 1000;
if (gst_buffer_get_size (buffer) == 0) {
GstClockTime const opus_plc_alignment = 2500 * GST_USECOND;
GstClockTime aligned_missing_duration;
GstClockTime missing_duration = GST_BUFFER_DURATION (buffer);
GST_DEBUG_OBJECT (dec,
"missing buffer, doing PLC duration %" GST_TIME_FORMAT
" plus leftover %" GST_TIME_FORMAT, GST_TIME_ARGS (missing_duration),
GST_TIME_ARGS (dec->leftover_plc_duration));
/* add the leftover PLC duration to that of the buffer */
missing_duration += dec->leftover_plc_duration;
/* align the combined buffer and leftover PLC duration to multiples
* of 2.5ms, always rounding down, and store excess duration for later */
aligned_missing_duration =
(missing_duration / opus_plc_alignment) * opus_plc_alignment;
dec->leftover_plc_duration = missing_duration - aligned_missing_duration;
/* Opus' PLC cannot operate with less than 2.5ms; skip PLC
* and accumulate the missing duration in the leftover_plc_duration
* for the next PLC attempt */
if (aligned_missing_duration < opus_plc_alignment) {
GST_DEBUG_OBJECT (dec,
"current duration %" GST_TIME_FORMAT
" of missing data not enough for PLC (minimum needed: %"
GST_TIME_FORMAT ") - skipping", GST_TIME_ARGS (missing_duration),
GST_TIME_ARGS (opus_plc_alignment));
goto done;
}
/* convert the duration (in nanoseconds) to sample count */
samples =
gst_util_uint64_scale_int (aligned_missing_duration, dec->sample_rate,
GST_SECOND);
GST_DEBUG_OBJECT (dec,
"calculated PLC frame length: %" GST_TIME_FORMAT
" num frame samples: %d new leftover: %" GST_TIME_FORMAT,
GST_TIME_ARGS (aligned_missing_duration), samples,
GST_TIME_ARGS (dec->leftover_plc_duration));
} else {
/* use maximum size (120 ms) as the number of returned samples is
not constant over the stream. */
samples = 120 * dec->sample_rate / 1000;
}
packet_size = samples * dec->n_channels * 2;
outbuf =
@ -462,7 +507,7 @@ opus_dec_chain_parse_data (GstOpusDec * dec, GstBuffer * buffer)
out_data = (gint16 *) omap.data;
if (dec->use_inband_fec) {
if (dec->last_buffer) {
if (gst_buffer_get_size (dec->last_buffer) > 0) {
/* normal delayed decode */
GST_LOG_OBJECT (dec, "FEC enabled, decoding last delayed buffer");
n = opus_multistream_decode (dec->state, data, size, out_data, samples,

2
ext/opus/gstopusdec.h
View file

@ -71,6 +71,8 @@ struct _GstOpusDec {
gboolean use_inband_fec;
GstBuffer *last_buffer;
gboolean primed;
guint64 leftover_plc_duration;
};
struct _GstOpusDecClass {