[FFmpeg-devel] [PATCH 3/3] avformat/movenc: handle EAC-3 extension bits for Atmos

[James Almer <jamrial@gmail.com>]

From: nyanmisaka <nst799610810@gmail.com>

Fixes commit #9996.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavformat/movenc.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 25360b004d..b546c8b545 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -393,6 +393,10 @@ struct eac3_info {
         uint16_t chan_loc;
         /* if there is no dependent substream, then one bit reserved instead */
     } substream[1]; /* TODO: support 8 independent substreams */
+    /* indicates the enhanced AC-3 extension, 1 bit */
+    uint8_t eac3_extension_type_a;
+    /* indicates the decoding complexity, 8 bits */
+    uint8_t complexity_index_type_a;
 };
 
 static int mov_write_ac3_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *track)
@@ -474,6 +478,9 @@ static int handle_eac3(MOVMuxContext *mov, AVPacket *pkt, MOVTrack *track)
     info->data_rate = FFMAX(info->data_rate, hdr->bit_rate / 1000);
     info->ac3_bit_rate_code = FFMAX(info->ac3_bit_rate_code,
                                     hdr->ac3_bit_rate_code);
+    info->eac3_extension_type_a   = hdr->eac3_extension_type_a;
+    info->complexity_index_type_a = hdr->complexity_index_type_a;
+
     num_blocks = hdr->num_blocks;
 
     if (!info->ec3_done) {
@@ -532,8 +539,6 @@ static int handle_eac3(MOVMuxContext *mov, AVPacket *pkt, MOVTrack *track)
             int parent = hdr->substreamid;
 
             while (cumul_size != pkt->size) {
-                GetBitContext gbc;
-                int i;
                 ret = avpriv_ac3_parse_header(&hdr, pkt->data + cumul_size, pkt->size - cumul_size);
                 if (ret < 0)
                     goto end;
@@ -544,20 +549,9 @@ static int handle_eac3(MOVMuxContext *mov, AVPacket *pkt, MOVTrack *track)
                 info->substream[parent].num_dep_sub++;
                 ret /= 8;
 
-                /* header is parsed up to lfeon, but custom channel map may be needed */
-                init_get_bits8(&gbc, pkt->data + cumul_size + ret, pkt->size - cumul_size - ret);
-                /* skip bsid */
-                skip_bits(&gbc, 5);
-                /* skip volume control params */
-                for (i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
-                    skip_bits(&gbc, 5); // skip dialog normalization
-                    if (get_bits1(&gbc)) {
-                        skip_bits(&gbc, 8); // skip compression gain word
-                    }
-                }
                 /* get the dependent stream channel map, if exists */
-                if (get_bits1(&gbc))
-                    info->substream[parent].chan_loc |= (get_bits(&gbc, 16) >> 5) & 0x1f;
+                if (hdr->channel_map_present)
+                    info->substream[parent].chan_loc |= (hdr->channel_map >> 5) & 0x1f;
                 else
                     info->substream[parent].chan_loc |= hdr->channel_mode;
                 cumul_size += hdr->frame_size;
@@ -614,7 +608,7 @@ static int mov_write_eac3_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
     }
 
     info = track->eac3_priv;
-    size = 2 + ((34 * (info->num_ind_sub + 1) + 7) >> 3);
+    size = 2 + ((32 * (info->num_ind_sub + 1) + 7 + 1 + 8) >> 3);
     buf = av_malloc(size);
     if (!buf) {
         return AVERROR(ENOMEM);
@@ -639,6 +633,11 @@ static int mov_write_eac3_tag(AVFormatContext *s, AVIOContext *pb, MOVTrack *tra
             put_bits(&pbc, 9, info->substream[i].chan_loc);
         }
     }
+    if (info->eac3_extension_type_a == 1) {
+        put_bits(&pbc, 7, 0); /* reserved */
+        put_bits(&pbc, 1, info->eac3_extension_type_a);
+        put_bits(&pbc, 8, info->complexity_index_type_a);
+    }
     flush_put_bits(&pbc);
     size = put_bytes_output(&pbc);
 
-- 
2.49.0

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