]> git.sesse.net Git - ffmpeg/blobdiff - libavcodec/ac3enc.c
Merge remote-tracking branch 'qatar/master'
[ffmpeg] / libavcodec / ac3enc.c
index df847b8a120d60335918f34db25a65ce8f1e2d76..44c16073a20f8ef9e69dcc83dc29dbd4b2aaf4d7 100644 (file)
@@ -526,20 +526,47 @@ static void encode_exponents(AC3EncodeContext *s)
 }
 
 
+/**
+ * Count exponent bits based on bandwidth, coupling, and exponent strategies.
+ */
+static int count_exponent_bits(AC3EncodeContext *s)
+{
+    int blk, ch;
+    int nb_groups, bit_count;
+
+    bit_count = 0;
+    for (blk = 0; blk < s->num_blocks; blk++) {
+        AC3Block *block = &s->blocks[blk];
+        for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
+            int exp_strategy = s->exp_strategy[ch][blk];
+            int cpl          = (ch == CPL_CH);
+            int nb_coefs     = block->end_freq[ch] - s->start_freq[ch];
+
+            if (exp_strategy == EXP_REUSE)
+                continue;
+
+            nb_groups = exponent_group_tab[cpl][exp_strategy-1][nb_coefs];
+            bit_count += 4 + (nb_groups * 7);
+        }
+    }
+
+    return bit_count;
+}
+
+
 /**
  * Group exponents.
  * 3 delta-encoded exponents are in each 7-bit group. The number of groups
  * varies depending on exponent strategy and bandwidth.
  */
-static void group_exponents(AC3EncodeContext *s)
+void ff_ac3_group_exponents(AC3EncodeContext *s)
 {
     int blk, ch, i, cpl;
-    int group_size, nb_groups, bit_count;
+    int group_size, nb_groups;
     uint8_t *p;
     int delta0, delta1, delta2;
     int exp0, exp1;
 
-    bit_count = 0;
     for (blk = 0; blk < s->num_blocks; blk++) {
         AC3Block *block = &s->blocks[blk];
         for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
@@ -549,7 +576,6 @@ static void group_exponents(AC3EncodeContext *s)
             cpl = (ch == CPL_CH);
             group_size = exp_strategy + (exp_strategy == EXP_D45);
             nb_groups = exponent_group_tab[cpl][exp_strategy-1][block->end_freq[ch]-s->start_freq[ch]];
-            bit_count += 4 + (nb_groups * 7);
             p = block->exp[ch] + s->start_freq[ch] - cpl;
 
             /* DC exponent */
@@ -581,8 +607,6 @@ static void group_exponents(AC3EncodeContext *s)
             }
         }
     }
-
-    s->exponent_bits = bit_count;
 }
 
 
@@ -599,8 +623,6 @@ void ff_ac3_process_exponents(AC3EncodeContext *s)
 
     encode_exponents(s);
 
-    group_exponents(s);
-
     emms_c();
 }
 
@@ -759,6 +781,30 @@ static void count_frame_bits(AC3EncodeContext *s)
 
     /* header */
     if (s->eac3) {
+        if (opt->eac3_mixing_metadata) {
+            if (s->channel_mode > AC3_CHMODE_STEREO)
+                frame_bits += 2;
+            if (s->has_center)
+                frame_bits += 6;
+            if (s->has_surround)
+                frame_bits += 6;
+            frame_bits += s->lfe_on;
+            frame_bits += 1 + 1 + 2;
+            if (s->channel_mode < AC3_CHMODE_STEREO)
+                frame_bits++;
+            frame_bits++;
+        }
+        if (opt->eac3_info_metadata) {
+            frame_bits += 3 + 1 + 1;
+            if (s->channel_mode == AC3_CHMODE_STEREO)
+                frame_bits += 2 + 2;
+            if (s->channel_mode >= AC3_CHMODE_2F2R)
+                frame_bits += 2;
+            frame_bits++;
+            if (opt->audio_production_info)
+                frame_bits += 5 + 2 + 1;
+            frame_bits++;
+        }
         /* coupling */
         if (s->channel_mode > AC3_CHMODE_MONO) {
             frame_bits++;
@@ -818,9 +864,9 @@ static void count_frame_bits(AC3EncodeContext *s)
         if (block->cpl_in_use) {
             for (ch = 1; ch <= s->fbw_channels; ch++) {
                 if (block->channel_in_cpl[ch]) {
-                    if (!s->eac3 || block->new_cpl_coords != 2)
+                    if (!s->eac3 || block->new_cpl_coords[ch] != 2)
                         frame_bits++;
-                    if (block->new_cpl_coords) {
+                    if (block->new_cpl_coords[ch]) {
                         frame_bits += 2;
                         frame_bits += (4 + 4) * s->num_cpl_bands;
                     }
@@ -1071,6 +1117,8 @@ int ff_ac3_compute_bit_allocation(AC3EncodeContext *s)
 {
     count_frame_bits(s);
 
+    s->exponent_bits = count_exponent_bits(s);
+
     bit_alloc_masking(s);
 
     return cbr_bit_allocation(s);
@@ -1346,9 +1394,9 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
     if (block->cpl_in_use) {
         for (ch = 1; ch <= s->fbw_channels; ch++) {
             if (block->channel_in_cpl[ch]) {
-                if (!s->eac3 || block->new_cpl_coords != 2)
-                    put_bits(&s->pb, 1, block->new_cpl_coords);
-                if (block->new_cpl_coords) {
+                if (!s->eac3 || block->new_cpl_coords[ch] != 2)
+                    put_bits(&s->pb, 1, block->new_cpl_coords[ch]);
+                if (block->new_cpl_coords[ch]) {
                     put_bits(&s->pb, 2, block->cpl_master_exp[ch]);
                     for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
                         put_bits(&s->pb, 4, block->cpl_coord_exp [ch][bnd]);
@@ -1616,9 +1664,9 @@ static void dprint_options(AC3EncodeContext *s)
     if (opt->audio_production_info) {
         av_dlog(avctx, "mixing_level: %ddB\n", opt->mixing_level);
         switch (opt->room_type) {
-        case 0:  av_strlcpy(strbuf, "notindicated", 32); break;
-        case 1:  av_strlcpy(strbuf, "large", 32);        break;
-        case 2:  av_strlcpy(strbuf, "small", 32);        break;
+        case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
+        case AC3ENC_OPT_LARGE_ROOM:    av_strlcpy(strbuf, "large", 32);        break;
+        case AC3ENC_OPT_SMALL_ROOM:    av_strlcpy(strbuf, "small", 32);        break;
         default: snprintf(strbuf, 32, "ERROR (%d)", opt->room_type);
         }
         av_dlog(avctx, "room_type: %s\n", strbuf);
@@ -1630,9 +1678,9 @@ static void dprint_options(AC3EncodeContext *s)
     av_dlog(avctx, "dialnorm: %ddB\n", opt->dialogue_level);
     if (s->channel_mode == AC3_CHMODE_STEREO) {
         switch (opt->dolby_surround_mode) {
-        case 0:  av_strlcpy(strbuf, "notindicated", 32); break;
-        case 1:  av_strlcpy(strbuf, "on", 32);           break;
-        case 2:  av_strlcpy(strbuf, "off", 32);          break;
+        case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
+        case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
+        case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
         default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_mode);
         }
         av_dlog(avctx, "dsur_mode: %s\n", strbuf);
@@ -1644,9 +1692,9 @@ static void dprint_options(AC3EncodeContext *s)
     if (s->bitstream_id == 6) {
         if (opt->extended_bsi_1) {
             switch (opt->preferred_stereo_downmix) {
-            case 0:  av_strlcpy(strbuf, "notindicated", 32); break;
-            case 1:  av_strlcpy(strbuf, "ltrt", 32);         break;
-            case 2:  av_strlcpy(strbuf, "loro", 32);         break;
+            case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
+            case AC3ENC_OPT_DOWNMIX_LTRT:  av_strlcpy(strbuf, "ltrt", 32);         break;
+            case AC3ENC_OPT_DOWNMIX_LORO:  av_strlcpy(strbuf, "loro", 32);         break;
             default: snprintf(strbuf, 32, "ERROR (%d)", opt->preferred_stereo_downmix);
             }
             av_dlog(avctx, "dmix_mode: %s\n", strbuf);
@@ -1663,23 +1711,23 @@ static void dprint_options(AC3EncodeContext *s)
         }
         if (opt->extended_bsi_2) {
             switch (opt->dolby_surround_ex_mode) {
-            case 0:  av_strlcpy(strbuf, "notindicated", 32); break;
-            case 1:  av_strlcpy(strbuf, "on", 32);           break;
-            case 2:  av_strlcpy(strbuf, "off", 32);          break;
+            case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
+            case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
+            case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_surround_ex_mode);
             }
             av_dlog(avctx, "dsurex_mode: %s\n", strbuf);
             switch (opt->dolby_headphone_mode) {
-            case 0:  av_strlcpy(strbuf, "notindicated", 32); break;
-            case 1:  av_strlcpy(strbuf, "on", 32);           break;
-            case 2:  av_strlcpy(strbuf, "off", 32);          break;
+            case AC3ENC_OPT_NOT_INDICATED: av_strlcpy(strbuf, "notindicated", 32); break;
+            case AC3ENC_OPT_MODE_ON:       av_strlcpy(strbuf, "on", 32);           break;
+            case AC3ENC_OPT_MODE_OFF:      av_strlcpy(strbuf, "off", 32);          break;
             default: snprintf(strbuf, 32, "ERROR (%d)", opt->dolby_headphone_mode);
             }
             av_dlog(avctx, "dheadphone_mode: %s\n", strbuf);
 
             switch (opt->ad_converter_type) {
-            case 0:  av_strlcpy(strbuf, "standard", 32); break;
-            case 1:  av_strlcpy(strbuf, "hdcd", 32);     break;
+            case AC3ENC_OPT_ADCONV_STANDARD: av_strlcpy(strbuf, "standard", 32); break;
+            case AC3ENC_OPT_ADCONV_HDCD:     av_strlcpy(strbuf, "hdcd", 32);     break;
             default: snprintf(strbuf, 32, "ERROR (%d)", opt->ad_converter_type);
             }
             av_dlog(avctx, "ad_conv_type: %s\n", strbuf);
@@ -1736,21 +1784,147 @@ int ff_ac3_validate_metadata(AC3EncodeContext *s)
     AVCodecContext *avctx = s->avctx;
     AC3EncOptions *opt = &s->options;
 
-    /* validate mixing levels */
-    if (s->has_center) {
-        validate_mix_level(avctx, "center_mix_level", &opt->center_mix_level,
-                           cmixlev_options, CMIXLEV_NUM_OPTIONS, 1, 0,
-                           &s->center_mix_level);
+    opt->audio_production_info = 0;
+    opt->extended_bsi_1        = 0;
+    opt->extended_bsi_2        = 0;
+    opt->eac3_mixing_metadata  = 0;
+    opt->eac3_info_metadata    = 0;
+
+    /* determine mixing metadata / xbsi1 use */
+    if (s->channel_mode > AC3_CHMODE_STEREO && opt->preferred_stereo_downmix != AC3ENC_OPT_NONE) {
+        opt->extended_bsi_1       = 1;
+        opt->eac3_mixing_metadata = 1;
+    }
+    if (s->has_center &&
+        (opt->ltrt_center_mix_level >= 0 || opt->loro_center_mix_level >= 0)) {
+        opt->extended_bsi_1       = 1;
+        opt->eac3_mixing_metadata = 1;
+    }
+    if (s->has_surround &&
+        (opt->ltrt_surround_mix_level >= 0 || opt->loro_surround_mix_level >= 0)) {
+        opt->extended_bsi_1       = 1;
+        opt->eac3_mixing_metadata = 1;
+    }
+
+    if (s->eac3) {
+        /* determine info metadata use */
+        if (avctx->audio_service_type != AV_AUDIO_SERVICE_TYPE_MAIN)
+            opt->eac3_info_metadata = 1;
+        if (opt->copyright != AC3ENC_OPT_NONE || opt->original != AC3ENC_OPT_NONE)
+            opt->eac3_info_metadata = 1;
+        if (s->channel_mode == AC3_CHMODE_STEREO &&
+            (opt->dolby_headphone_mode != AC3ENC_OPT_NONE || opt->dolby_surround_mode != AC3ENC_OPT_NONE))
+            opt->eac3_info_metadata = 1;
+        if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
+            opt->eac3_info_metadata = 1;
+        if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE ||
+            opt->ad_converter_type != AC3ENC_OPT_NONE) {
+            opt->audio_production_info = 1;
+            opt->eac3_info_metadata    = 1;
+        }
+    } else {
+        /* determine audio production info use */
+        if (opt->mixing_level != AC3ENC_OPT_NONE || opt->room_type != AC3ENC_OPT_NONE)
+            opt->audio_production_info = 1;
+
+        /* determine xbsi2 use */
+        if (s->channel_mode >= AC3_CHMODE_2F2R && opt->dolby_surround_ex_mode != AC3ENC_OPT_NONE)
+            opt->extended_bsi_2 = 1;
+        if (s->channel_mode == AC3_CHMODE_STEREO && opt->dolby_headphone_mode != AC3ENC_OPT_NONE)
+            opt->extended_bsi_2 = 1;
+        if (opt->ad_converter_type != AC3ENC_OPT_NONE)
+            opt->extended_bsi_2 = 1;
+    }
+
+    /* validate AC-3 mixing levels */
+    if (!s->eac3) {
+        if (s->has_center) {
+            validate_mix_level(avctx, "center_mix_level", &opt->center_mix_level,
+                            cmixlev_options, CMIXLEV_NUM_OPTIONS, 1, 0,
+                            &s->center_mix_level);
+        }
+        if (s->has_surround) {
+            validate_mix_level(avctx, "surround_mix_level", &opt->surround_mix_level,
+                            surmixlev_options, SURMIXLEV_NUM_OPTIONS, 1, 0,
+                            &s->surround_mix_level);
+        }
+    }
+
+    /* validate extended bsi 1 / mixing metadata */
+    if (opt->extended_bsi_1 || opt->eac3_mixing_metadata) {
+        /* default preferred stereo downmix */
+        if (opt->preferred_stereo_downmix == AC3ENC_OPT_NONE)
+            opt->preferred_stereo_downmix = AC3ENC_OPT_NOT_INDICATED;
+        if (!s->eac3 || s->has_center) {
+            /* validate Lt/Rt center mix level */
+            validate_mix_level(avctx, "ltrt_center_mix_level",
+                               &opt->ltrt_center_mix_level, extmixlev_options,
+                               EXTMIXLEV_NUM_OPTIONS, 5, 0,
+                               &s->ltrt_center_mix_level);
+            /* validate Lo/Ro center mix level */
+            validate_mix_level(avctx, "loro_center_mix_level",
+                               &opt->loro_center_mix_level, extmixlev_options,
+                               EXTMIXLEV_NUM_OPTIONS, 5, 0,
+                               &s->loro_center_mix_level);
+        }
+        if (!s->eac3 || s->has_surround) {
+            /* validate Lt/Rt surround mix level */
+            validate_mix_level(avctx, "ltrt_surround_mix_level",
+                               &opt->ltrt_surround_mix_level, extmixlev_options,
+                               EXTMIXLEV_NUM_OPTIONS, 6, 3,
+                               &s->ltrt_surround_mix_level);
+            /* validate Lo/Ro surround mix level */
+            validate_mix_level(avctx, "loro_surround_mix_level",
+                               &opt->loro_surround_mix_level, extmixlev_options,
+                               EXTMIXLEV_NUM_OPTIONS, 6, 3,
+                               &s->loro_surround_mix_level);
+        }
+    }
+
+    /* validate audio service type / channels combination */
+    if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
+         avctx->channels == 1) ||
+        ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
+          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY  ||
+          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
+         && avctx->channels > 1)) {
+        av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
+                                    "specified number of channels\n");
+        return AVERROR(EINVAL);
+    }
+
+    /* validate extended bsi 2 / info metadata */
+    if (opt->extended_bsi_2 || opt->eac3_info_metadata) {
+        /* default dolby headphone mode */
+        if (opt->dolby_headphone_mode == AC3ENC_OPT_NONE)
+            opt->dolby_headphone_mode = AC3ENC_OPT_NOT_INDICATED;
+        /* default dolby surround ex mode */
+        if (opt->dolby_surround_ex_mode == AC3ENC_OPT_NONE)
+            opt->dolby_surround_ex_mode = AC3ENC_OPT_NOT_INDICATED;
+        /* default A/D converter type */
+        if (opt->ad_converter_type == AC3ENC_OPT_NONE)
+            opt->ad_converter_type = AC3ENC_OPT_ADCONV_STANDARD;
     }
-    if (s->has_surround) {
-        validate_mix_level(avctx, "surround_mix_level", &opt->surround_mix_level,
-                           surmixlev_options, SURMIXLEV_NUM_OPTIONS, 1, 0,
-                           &s->surround_mix_level);
+
+    /* copyright & original defaults */
+    if (!s->eac3 || opt->eac3_info_metadata) {
+        /* default copyright */
+        if (opt->copyright == AC3ENC_OPT_NONE)
+            opt->copyright = AC3ENC_OPT_OFF;
+        /* default original */
+        if (opt->original == AC3ENC_OPT_NONE)
+            opt->original = AC3ENC_OPT_ON;
     }
 
-    /* set audio production info flag */
-    if (opt->mixing_level >= 0 || opt->room_type >= 0) {
-        if (opt->mixing_level < 0) {
+    /* dolby surround mode default */
+    if (!s->eac3 || opt->eac3_info_metadata) {
+        if (opt->dolby_surround_mode == AC3ENC_OPT_NONE)
+            opt->dolby_surround_mode = AC3ENC_OPT_NOT_INDICATED;
+    }
+
+    /* validate audio production info */
+    if (opt->audio_production_info) {
+        if (opt->mixing_level == AC3ENC_OPT_NONE) {
             av_log(avctx, AV_LOG_ERROR, "mixing_level must be set if "
                    "room_type is set\n");
             return AVERROR(EINVAL);
@@ -1761,68 +1935,12 @@ int ff_ac3_validate_metadata(AC3EncodeContext *s)
             return AVERROR(EINVAL);
         }
         /* default room type */
-        if (opt->room_type < 0)
-            opt->room_type = 0;
-        opt->audio_production_info = 1;
-    } else {
-        opt->audio_production_info = 0;
-    }
-
-    /* set extended bsi 1 flag */
-    if ((s->has_center || s->has_surround) &&
-        (opt->preferred_stereo_downmix >= 0 ||
-         opt->ltrt_center_mix_level   >= 0 ||
-         opt->ltrt_surround_mix_level >= 0 ||
-         opt->loro_center_mix_level   >= 0 ||
-         opt->loro_surround_mix_level >= 0)) {
-        /* default preferred stereo downmix */
-        if (opt->preferred_stereo_downmix < 0)
-            opt->preferred_stereo_downmix = 0;
-        /* validate Lt/Rt center mix level */
-        validate_mix_level(avctx, "ltrt_center_mix_level",
-                           &opt->ltrt_center_mix_level, extmixlev_options,
-                           EXTMIXLEV_NUM_OPTIONS, 5, 0,
-                           &s->ltrt_center_mix_level);
-        /* validate Lt/Rt surround mix level */
-        validate_mix_level(avctx, "ltrt_surround_mix_level",
-                           &opt->ltrt_surround_mix_level, extmixlev_options,
-                           EXTMIXLEV_NUM_OPTIONS, 6, 3,
-                           &s->ltrt_surround_mix_level);
-        /* validate Lo/Ro center mix level */
-        validate_mix_level(avctx, "loro_center_mix_level",
-                           &opt->loro_center_mix_level, extmixlev_options,
-                           EXTMIXLEV_NUM_OPTIONS, 5, 0,
-                           &s->loro_center_mix_level);
-        /* validate Lo/Ro surround mix level */
-        validate_mix_level(avctx, "loro_surround_mix_level",
-                           &opt->loro_surround_mix_level, extmixlev_options,
-                           EXTMIXLEV_NUM_OPTIONS, 6, 3,
-                           &s->loro_surround_mix_level);
-        opt->extended_bsi_1 = 1;
-    } else {
-        opt->extended_bsi_1 = 0;
-    }
-
-    /* set extended bsi 2 flag */
-    if (opt->dolby_surround_ex_mode >= 0 ||
-        opt->dolby_headphone_mode   >= 0 ||
-        opt->ad_converter_type      >= 0) {
-        /* default dolby surround ex mode */
-        if (opt->dolby_surround_ex_mode < 0)
-            opt->dolby_surround_ex_mode = 0;
-        /* default dolby headphone mode */
-        if (opt->dolby_headphone_mode < 0)
-            opt->dolby_headphone_mode = 0;
-        /* default A/D converter type */
-        if (opt->ad_converter_type < 0)
-            opt->ad_converter_type = 0;
-        opt->extended_bsi_2 = 1;
-    } else {
-        opt->extended_bsi_2 = 0;
+        if (opt->room_type == AC3ENC_OPT_NONE)
+            opt->room_type = AC3ENC_OPT_NOT_INDICATED;
     }
 
     /* set bitstream id for alternate bitstream syntax */
-    if (opt->extended_bsi_1 || opt->extended_bsi_2) {
+    if (!s->eac3 && (opt->extended_bsi_1 || opt->extended_bsi_2)) {
         if (s->bitstream_id > 8 && s->bitstream_id < 11) {
             static int warn_once = 1;
             if (warn_once) {
@@ -2041,29 +2159,15 @@ static av_cold int validate_options(AC3EncodeContext *s)
     if (s->cutoff > (s->sample_rate >> 1))
         s->cutoff = s->sample_rate >> 1;
 
-    /* validate audio service type / channels combination */
-    if ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_KARAOKE &&
-         avctx->channels == 1) ||
-        ((avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_COMMENTARY ||
-          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_EMERGENCY  ||
-          avctx->audio_service_type == AV_AUDIO_SERVICE_TYPE_VOICE_OVER)
-         && avctx->channels > 1)) {
-        av_log(avctx, AV_LOG_ERROR, "invalid audio service type for the "
-                                    "specified number of channels\n");
-        return AVERROR(EINVAL);
-    }
-
-    if (!s->eac3) {
-        ret = ff_ac3_validate_metadata(s);
-        if (ret)
-            return ret;
-    }
+    ret = ff_ac3_validate_metadata(s);
+    if (ret)
+        return ret;
 
     s->rematrixing_enabled = s->options.stereo_rematrixing &&
                              (s->channel_mode == AC3_CHMODE_STEREO);
 
     s->cpl_enabled = s->options.channel_coupling &&
-                     s->channel_mode >= AC3_CHMODE_STEREO && !s->fixed_point;
+                     s->channel_mode >= AC3_CHMODE_STEREO;
 
     return 0;
 }
@@ -2104,12 +2208,16 @@ static av_cold void set_bandwidth(AC3EncodeContext *s)
 
     /* initialize coupling strategy */
     if (s->cpl_enabled) {
-        if (s->options.cpl_start >= 0) {
+        if (s->options.cpl_start != AC3ENC_OPT_AUTO) {
             cpl_start = s->options.cpl_start;
         } else {
             cpl_start = ac3_coupling_start_tab[s->channel_mode-2][s->bit_alloc.sr_code][s->frame_size_code/2];
-            if (cpl_start < 0)
-                s->cpl_enabled = 0;
+            if (cpl_start < 0) {
+                if (s->options.channel_coupling == AC3ENC_OPT_AUTO)
+                    s->cpl_enabled = 0;
+                else
+                    cpl_start = 15;
+            }
         }
     }
     if (s->cpl_enabled) {