[FFmpeg-cvslog] avformat/iamf_writer: fix setting num_samples_per_frame for OPUS

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Wed Dec 11 13:30:23 2024 -0300| [76049d1c4564a6a03c467b1f9b0bc853bc971769] | committer: James Almer

avformat/iamf_writer: fix setting num_samples_per_frame for OPUS

As per section 3.11.1 of the IAMF spec, the sample rate used in Codec Config
for Opus shall be 48kHz, regardless of the original sample rate used during
encoding.

Signed-off-by: James Almer <jamrial at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=76049d1c4564a6a03c467b1f9b0bc853bc971769
---

 libavformat/iamf_writer.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/libavformat/iamf_writer.c b/libavformat/iamf_writer.c
index f15dabcb3e..467f839baf 100644
--- a/libavformat/iamf_writer.c
+++ b/libavformat/iamf_writer.c
@@ -112,9 +112,17 @@ static int fill_codec_config(IAMFContext *iamf, const AVStreamGroup *stg,
     int j, ret = 0;
 
     codec_config->codec_id = st->codecpar->codec_id;
-    codec_config->sample_rate = st->codecpar->sample_rate;
     codec_config->codec_tag = st->codecpar->codec_tag;
-    codec_config->nb_samples = st->codecpar->frame_size;
+    switch (codec_config->codec_id) {
+    case AV_CODEC_ID_OPUS:
+        codec_config->sample_rate = 48000;
+        codec_config->nb_samples = av_rescale(st->codecpar->frame_size, 48000, st->codecpar->sample_rate);
+        break;
+    default:
+        codec_config->sample_rate = st->codecpar->sample_rate;
+        codec_config->nb_samples = st->codecpar->frame_size;
+        break;
+    }
     populate_audio_roll_distance(codec_config);
     if (st->codecpar->extradata_size) {
         codec_config->extradata = av_memdup(st->codecpar->extradata, st->codecpar->extradata_size);
@@ -183,9 +191,9 @@ static int add_param_definition(IAMFContext *iamf, AVIAMFParamDefinition *param,
     }
     if (codec_config) {
         if (!param->duration)
-            param->duration = codec_config->nb_samples;
+            param->duration = av_rescale(codec_config->nb_samples, param->parameter_rate, codec_config->sample_rate);
         if (!param->constant_subblock_duration)
-            param->constant_subblock_duration = codec_config->nb_samples;
+            param->constant_subblock_duration = av_rescale(codec_config->nb_samples, param->parameter_rate, codec_config->sample_rate);
     }
 
     param_definition = av_mallocz(sizeof(*param_definition));