[FFmpeg-cvslog] avcodec/ac3dec: add a flush callback for the ac3 and eac3 decoders

[James Almer]

ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Wed Feb 12 19:04:30 2025 -0300| [045a8b15b19ec7f872fb01cfb986faeaa26cb8bb] | committer: James Almer

avcodec/ac3dec: add a flush callback for the ac3 and eac3 decoders

Fixes ticket #10732

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=045a8b15b19ec7f872fb01cfb986faeaa26cb8bb
---

 libavcodec/ac3dec.c       | 10 ++++++++++
 libavcodec/ac3dec.h       |  1 +
 libavcodec/ac3dec_fixed.c |  1 +
 libavcodec/ac3dec_float.c |  2 ++
 4 files changed, 14 insertions(+)

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index ff8cbfb0b4..2cf82abc19 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -252,6 +252,16 @@ static av_cold int ac3_decode_init(AVCodecContext *avctx)
     return 0;
 }
 
+static av_cold void ac3_decode_flush(AVCodecContext *avctx)
+{
+    AC3DecodeContext *s = avctx->priv_data;
+
+    memset(&s->frame_type, 0, sizeof(*s) - offsetof(AC3DecodeContext, frame_type));
+
+    AC3_RENAME(ff_kbd_window_init)(s->window, 5.0, 256);
+    av_lfg_init(&s->dith_state, 0);
+}
+
 /**
  * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
  * GetBitContext within AC3DecodeContext must point to
diff --git a/libavcodec/ac3dec.h b/libavcodec/ac3dec.h
index 0a6bba7c63..4042a99b80 100644
--- a/libavcodec/ac3dec.h
+++ b/libavcodec/ac3dec.h
@@ -96,6 +96,7 @@ typedef struct AC3DecodeContext {
     SHORTFLOAT *downmix_coeffs[2];              ///< stereo downmix coefficients
 
 // Start of flushable fields.
+// frame_type must be the flushable field, or the offset changed in ac3_decode_flush().
 
 ///@name Bit stream information
 ///@{
diff --git a/libavcodec/ac3dec_fixed.c b/libavcodec/ac3dec_fixed.c
index e0db9b2260..e284140e74 100644
--- a/libavcodec/ac3dec_fixed.c
+++ b/libavcodec/ac3dec_fixed.c
@@ -181,6 +181,7 @@ const FFCodec ff_ac3_fixed_decoder = {
     .p.priv_class   = &ac3_decoder_class,
     .priv_data_size = sizeof (AC3DecodeContext),
     .init           = ac3_decode_init,
+    .flush          = ac3_decode_flush,
     .close          = ac3_decode_end,
     FF_CODEC_DECODE_CB(ac3_decode_frame),
     .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF |
diff --git a/libavcodec/ac3dec_float.c b/libavcodec/ac3dec_float.c
index 53d9d472c4..31f5590729 100644
--- a/libavcodec/ac3dec_float.c
+++ b/libavcodec/ac3dec_float.c
@@ -70,6 +70,7 @@ const FFCodec ff_ac3_decoder = {
     .p.id           = AV_CODEC_ID_AC3,
     .priv_data_size = sizeof (AC3DecodeContext),
     .init           = ac3_decode_init,
+    .flush          = ac3_decode_flush,
     .close          = ac3_decode_end,
     FF_CODEC_DECODE_CB(ac3_decode_frame),
     .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF |
@@ -88,6 +89,7 @@ const FFCodec ff_eac3_decoder = {
     .p.id           = AV_CODEC_ID_EAC3,
     .priv_data_size = sizeof (AC3DecodeContext),
     .init           = ac3_decode_init,
+    .flush          = ac3_decode_flush,
     .close          = ac3_decode_end,
     FF_CODEC_DECODE_CB(ac3_decode_frame),
     .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF |