[FFmpeg-devel] [PATCH v2] avcodec/ac3dec: add a flush callback for the ac3 and eac3 decoders

[James Almer]

Fixes ticket #10732

Signed-off-by: James Almer <jamrial at gmail.com>
---
 libavcodec/ac3dec.c       | 10 ++++++++++
 libavcodec/ac3dec.h       | 40 ++++++++++++++++++++++-----------------
 libavcodec/ac3dec_fixed.c |  1 +
 libavcodec/ac3dec_float.c |  2 ++
 4 files changed, 36 insertions(+), 17 deletions(-)

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 98de7b5abf..cc6d1a118e 100644
--- a/libavcodec/ac3dec.h
+++ b/libavcodec/ac3dec.h
@@ -75,8 +75,30 @@ typedef struct AC3DecodeContext {
     AVCodecContext *avctx;                  ///< parent context
     GetBitContext gbc;                      ///< bitstream reader
 
+    AVTXContext *tx_128, *tx_256;
+    av_tx_fn tx_fn_128, tx_fn_256;
+
+///@name Optimization
+    BswapDSPContext bdsp;
+#if USE_FIXED
+    AVFixedDSPContext *fdsp;
+#else
+    AVFloatDSPContext *fdsp;
+#endif
+    AC3DSPContext ac3dsp;
+    FmtConvertContext fmt_conv;             ///< optimized conversion functions
+///@}
+
+    INTFLOAT *xcfptr[AC3_MAX_CHANNELS];
+    INTFLOAT *dlyptr[AC3_MAX_CHANNELS];
+
+    AVChannelLayout downmix_layout;
+    SHORTFLOAT *downmix_coeffs[2];              ///< stereo downmix coefficients
+
+// Start of flushable fields
 ///@name Bit stream information
 ///@{
+    // frame_type must be first
     int frame_type;                         ///< frame type                             (strmtyp)
     int substreamid;                        ///< substream identification
     int superframe_size;                    ///< current superframe size, in bytes
@@ -164,7 +186,6 @@ typedef struct AC3DecodeContext {
     int fbw_channels;                           ///< number of full-bandwidth channels
     int channels;                               ///< number of total channels
     int lfe_ch;                                 ///< index of LFE channel
-    SHORTFLOAT *downmix_coeffs[2];              ///< stereo downmix coefficients
     int downmixed;                              ///< indicates if coeffs are currently downmixed
     int output_mode;                            ///< output channel configuration
     int prev_output_mode;                       ///< output channel configuration for previous frame
@@ -222,24 +243,9 @@ typedef struct AC3DecodeContext {
 
 ///@name IMDCT
     int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)
-    AVTXContext *tx_128, *tx_256;
-    av_tx_fn tx_fn_128, tx_fn_256;
-///@}
-
-///@name Optimization
-    BswapDSPContext bdsp;
-#if USE_FIXED
-    AVFixedDSPContext *fdsp;
-#else
-    AVFloatDSPContext *fdsp;
-#endif
-    AC3DSPContext ac3dsp;
-    FmtConvertContext fmt_conv;             ///< optimized conversion functions
 ///@}
 
     SHORTFLOAT *outptr[AC3_MAX_CHANNELS];
-    INTFLOAT *xcfptr[AC3_MAX_CHANNELS];
-    INTFLOAT *dlyptr[AC3_MAX_CHANNELS];
 
 ///@name Aligned arrays
     DECLARE_ALIGNED(16, int,   fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];       ///< fixed-point transform coefficients
@@ -252,7 +258,7 @@ typedef struct AC3DecodeContext {
     DECLARE_ALIGNED(32, SHORTFLOAT, output_buffer)[EAC3_MAX_CHANNELS][AC3_BLOCK_SIZE * 6];  ///< final output buffer
 ///@}
 
-    AVChannelLayout downmix_layout;
+// End of flushable fields
 } AC3DecodeContext;
 
 /**
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 |
-- 
2.48.1