avcodec/ac3_parser{,_internal}: expose AC-3 bit_rate_code

Required by MP4's AC3SpecificBox and MPEG-TS AC-3 audio_descriptor,
of which the former is implemented in our MP4 writer.
Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>

libavcodec/ac3_parser.c

@@ -70,6 +70,7 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
         return AAC_AC3_PARSE_ERROR_BSID;
 
     hdr->num_blocks = 6;
+    hdr->ac3_bit_rate_code = -1;
 
     /* set default mix levels */
     hdr->center_mix_level   = 5;  // -4.5dB
@@ -89,6 +90,8 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
         if(frame_size_code > 37)
             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
 
+        hdr->ac3_bit_rate_code = (frame_size_code >> 1);
+
         skip_bits(gbc, 5); // skip bsid, already got it
 
         hdr->bitstream_mode = get_bits(gbc, 3);
@@ -106,7 +109,7 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
 
         hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
         hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
-        hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
+        hdr->bit_rate = (ff_ac3_bitrate_tab[hdr->ac3_bit_rate_code] * 1000) >> hdr->sr_shift;
         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
         hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
         hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;

libavcodec/ac3_parser_internal.h

@@ -60,6 +60,7 @@ typedef struct AC3HeaderInfo {
     uint8_t channels;
     uint16_t frame_size;
     uint64_t channel_layout;
+    int8_t ac3_bit_rate_code;
     /** @} */
 } AC3HeaderInfo;
 

libavcodec/version.h

@@ -29,7 +29,7 @@
 
 #include "version_major.h"
 
-#define LIBAVCODEC_VERSION_MINOR  34
+#define LIBAVCODEC_VERSION_MINOR  35
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \