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

[James Almer]

ffmpeg | branch: release/7.1 | James Almer <jamrial at gmail.com> | Wed Dec 11 13:30:23 2024 -0300| [b168ed9b146337e7bd3c218c5d1c0f7e88bf1315] | 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>
(cherry picked from commit 76049d1c4564a6a03c467b1f9b0bc853bc971769)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b168ed9b146337e7bd3c218c5d1c0f7e88bf1315
---

 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 1b620c38ee..0508c676d1 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));