[FFmpeg-devel] [PATCH 1/3] lavf/mp3dec: pass Xing gapless metadata to AVCodecParameters

[Jon Toohill]

Also removes decoder delay compensation from libmp3lame and mp3enc.
initial_padding specifies only encoder delay, decoder delay is
handled by start_skip_samples.
---
 libavcodec/libmp3lame.c | 2 +-
 libavformat/mp3dec.c    | 2 ++
 libavformat/mp3enc.c    | 9 ++++++---
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/libavcodec/libmp3lame.c b/libavcodec/libmp3lame.c
index 5642264..198ac94 100644
--- a/libavcodec/libmp3lame.c
+++ b/libavcodec/libmp3lame.c
@@ -137,7 +137,7 @@ static av_cold int mp3lame_encode_init(AVCodecContext *avctx)
     }
 
     /* get encoder delay */
-    avctx->initial_padding = lame_get_encoder_delay(s->gfp) + 528 + 1;
+    avctx->initial_padding = lame_get_encoder_delay(s->gfp);
     ff_af_queue_init(avctx, &s->afq);
 
     avctx->frame_size  = lame_get_framesize(s->gfp);
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 56c7f8c..345fa88 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -239,6 +239,8 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream *st,
 
         mp3->start_pad = v>>12;
         mp3->  end_pad = v&4095;
+        st->codecpar->initial_padding = mp3->start_pad;
+        st->codecpar->trailing_padding = mp3->end_pad;
         st->start_skip_samples = mp3->start_pad + 528 + 1;
         if (mp3->frames) {
             st->first_discard_sample = -mp3->end_pad + 528 + 1 + mp3->frames * (int64_t)spf;
diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c
index de63401..da70d13 100644
--- a/libavformat/mp3enc.c
+++ b/libavformat/mp3enc.c
@@ -248,11 +248,14 @@ static int mp3_write_xing(AVFormatContext *s)
     avio_w8(dyn_ctx, 0);      // unknown encoding flags
     avio_w8(dyn_ctx, 0);      // unknown abr/minimal bitrate
 
-    // encoder delay
-    if (par->initial_padding - 528 - 1 >= 1 << 12) {
+    // encoder delay/padding
+    if (par->initial_padding >= 1 << 12) {
         av_log(s, AV_LOG_WARNING, "Too many samples of initial padding.\n");
     }
-    avio_wb24(dyn_ctx, FFMAX(par->initial_padding - 528 - 1, 0)<<12);
+    if (par->trailing_padding >= 1 << 12) {
+        av_log(s, AV_LOG_WARNING, "Too many samples of trailing padding.\n");
+    }
+    avio_wb24(dyn_ctx, (par->initial_padding << 12) | (par->trailing_padding & 0xFFF));
 
     avio_w8(dyn_ctx,   0); // misc
     avio_w8(dyn_ctx,   0); // mp3gain
-- 
2.8.0.rc3.226.g39d4020