[FFmpeg-devel] [PR] avcodec/libvorbisenc: export priming and padding samples if needed (PR #21665)

[FFmpeg-devel] [PR] avcodec/libvorbisenc: export priming and padding samples if needed (PR #21665)

[James Almer via ffmpeg-devel]

PR #21665 opened by James Almer (jamrial)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21665
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21665.patch

Based on code from libopus and libfdk-aac encoder wrappers.


>From c85a57f9baf657fe548369c7befecacff138489a Mon Sep 17 00:00:00 2001
From: James Almer <jamrial@gmail.com>
Date: Fri, 6 Feb 2026 15:34:49 -0300
Subject: [PATCH] avcodec/libvorbisenc: export priming and padding samples if
 needed

Based on code from libopus and libfdk-aac encoder wrappers.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/libvorbisenc.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/libavcodec/libvorbisenc.c b/libavcodec/libvorbisenc.c
index 6aa1ec3b3c..50798122c1 100644
--- a/libavcodec/libvorbisenc.c
+++ b/libavcodec/libvorbisenc.c
@@ -23,6 +23,7 @@
 #include "libavutil/avassert.h"
 #include "libavutil/channel_layout.h"
 #include "libavutil/fifo.h"
+#include "libavutil/intreadwrite.h"
 #include "libavutil/mem.h"
 #include "libavutil/opt.h"
 #include "avcodec.h"
@@ -357,10 +358,11 @@ static int libvorbis_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
 
     duration = av_vorbis_parse_frame(s->vp, avpkt->data, avpkt->size);
     if (duration > 0) {
+        int discard_padding, delay = 0;
         /* we do not know encoder delay until we get the first packet from
          * libvorbis, so we have to update the AudioFrameQueue counts */
         if (!avctx->initial_padding && s->afq.frames) {
-            avctx->initial_padding    = duration;
+            avctx->initial_padding = delay = duration;
             av_assert0(!s->afq.remaining_delay);
             s->afq.frames->duration  += duration;
             if (s->afq.frames->pts != AV_NOPTS_VALUE)
@@ -368,6 +370,17 @@ static int libvorbis_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
             s->afq.remaining_samples += duration;
         }
         ff_af_queue_remove(&s->afq, duration, &avpkt->pts, &avpkt->duration);
+
+        discard_padding = duration - avpkt->duration;
+        if (delay > 0 || discard_padding > 0) {
+            uint8_t *side_data = av_packet_new_side_data(avpkt,
+                                                         AV_PKT_DATA_SKIP_SAMPLES,
+                                                         10);
+            if (!side_data)
+                return AVERROR(ENOMEM);
+            AV_WL32(side_data, delay);
+            AV_WL32(side_data + 4, discard_padding);
+        }
     }
 
     *got_packet_ptr = 1;
-- 
2.52.0

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