Signed-off-by: James Almer <jamr...@gmail.com>
---
libavcodec/libdcadec.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/libavcodec/libdcadec.c b/libavcodec/libdcadec.c
index 4bc3765..796826e 100644
--- a/libavcodec/libdcadec.c
+++ b/libavcodec/libdcadec.c
@@ -36,6 +36,8 @@ typedef struct DCADecContext {
int buffer_size;
} DCADecContext;
+static int downmix_warned = 0;
+
static int dcadec_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
@@ -131,6 +133,17 @@ static int dcadec_decode_frame(AVCodecContext *avctx, void
*data,
if (exss = dcadec_context_get_exss_info(s->ctx)) {
enum AVMatrixEncoding matrix_encoding = AV_MATRIX_ENCODING_NONE;
+ if (!downmix_warned) {
+ uint64_t layout = avctx->request_channel_layout;
+
+ if (((layout == AV_CH_LAYOUT_STEREO_DOWNMIX || layout ==
AV_CH_LAYOUT_STEREO) && !exss->embedded_stereo) ||
+ ( layout == AV_CH_LAYOUT_5POINT1 && !exss->embedded_6ch))
+ av_log(avctx, AV_LOG_WARNING, "%s downmix was requested but no
custom coefficients are available, "
+ "this may result in clipping\n",
+ layout == AV_CH_LAYOUT_5POINT1 ?
"5.1" : "stereo");
+ downmix_warned = 1;
+ }
+
switch(exss->matrix_encoding) {
case DCADEC_MATRIX_ENCODING_SURROUND:
matrix_encoding = AV_MATRIX_ENCODING_DOLBY;
@@ -195,6 +208,27 @@ static av_cold int dcadec_init(AVCodecContext *avctx)
if (avctx->flags & CODEC_FLAG_BITEXACT)
flags |= DCADEC_FLAG_CORE_BIT_EXACT;
+ if (avctx->request_channel_layout > 0 && avctx->request_channel_layout !=
AV_CH_LAYOUT_NATIVE) {
+ switch (avctx->request_channel_layout) {
+ case AV_CH_LAYOUT_STEREO:
+ case AV_CH_LAYOUT_STEREO_DOWNMIX:
+ /* libdcadec ignores the 2ch flag if used alone when no custom
downmix coefficients
+ are available, silently outputting a 5.1 downmix if possible
instead.
+ Using both the 2ch and 6ch flags together forces a 2ch downmix
using default
+ coefficients in such cases. This matches the behavior of the
6ch flag when used
+ alone, where a 5.1 downmix is generated if possible, regardless
of custom
+ coefficients being available or not. */
+ flags |= DCADEC_FLAG_KEEP_DMIX_2CH | DCADEC_FLAG_KEEP_DMIX_6CH;
+ break;
+ case AV_CH_LAYOUT_5POINT1:
+ flags |= DCADEC_FLAG_KEEP_DMIX_6CH;
+ break;
+ default:
+ av_log(avctx, AV_LOG_WARNING, "Invalid request_channel_layout\n");
+ break;
+ }
+ }
+
s->ctx = dcadec_context_create(flags);
if (!s->ctx)
return AVERROR(ENOMEM);
--
2.4.5
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