fix to use libFDKAAC signaling mode 1

It turned out that mode 1 is explicit, backward compatible signaling.
We don't have to implement it on our side.

src/aacenc.c

@@ -64,70 +64,6 @@ void aacenc_get_lib_info(LIB_INFO *info)
     free(lib_info);
 }
 
-static const unsigned aacenc_sampling_freq_tab[] = {
-    96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 
-    16000, 12000, 11025, 8000, 7350, 0, 0, 0
-};
-
-static
-unsigned sampling_freq_index(unsigned rate)
-{
-    unsigned i;
-    for (i = 0; aacenc_sampling_freq_tab[i]; ++i)
-        if (aacenc_sampling_freq_tab[i] == rate)
-            return i;
-    return 0xf;
-}
-
-/*
- * Append backward compatible SBR/PS signaling to implicit signaling ASC,
- * if SBR/PS is present.
- */
-int aacenc_mp4asc(const aacenc_param_t *params,
-                  const uint8_t *asc, uint32_t ascsize,
-                  uint8_t *outasc, uint32_t *outsize)
-{
-    unsigned asc_sfreq = aacenc_sampling_freq_tab[(asc[0]&0x7)<<1 |asc[1]>>7];
-    unsigned shift = aacenc_is_dual_rate_sbr(params);
-
-    switch (params->profile) {
-    case AOT_SBR:
-    case AOT_PS:
-        if (!shift)
-            break;
-        if (*outsize < ascsize + 3)
-            return -1;
-        memcpy(outasc, asc, ascsize);
-        /* syncExtensionType:11 (value:0x2b7) */
-        outasc[ascsize+0] = 0x2b << 1;
-        outasc[ascsize+1] = 0x7 << 5;
-        /* extensionAudioObjectType:5 (value:5)*/
-        outasc[ascsize+1] |= 5;
-        /* sbrPresentFlag:1 (value:1) */
-        outasc[ascsize+2] = 0x80;
-        /* extensionSamplingFrequencyIndex:4 */
-        outasc[ascsize+2] |= sampling_freq_index(asc_sfreq << shift) << 3;
-        if (params->profile == AOT_SBR) {
-            *outsize = ascsize + 3;
-            return 0;
-        }
-        if (*outsize < ascsize + 5)
-            return -1;
-        /* syncExtensionType:11 (value:0x548) */
-        outasc[ascsize+2] |= 0x5;
-        outasc[ascsize+3] = 0x48;
-        /* psPresentFlag:1 (value:1) */
-        outasc[ascsize+4] = 0x80;
-        *outsize = ascsize + 5;
-        return 0;
-    }
-    if (*outsize < ascsize)
-        return -1;
-    memcpy(outasc, asc, ascsize);
-    *outsize = ascsize;
-    return 0;
-}
-
 static
 int aacenc_channel_mode(const pcm_sample_description_t *format)
 {

src/aacenc.h

@@ -38,10 +38,6 @@ int aacenc_is_dual_rate_sbr(const aacenc_param_t *params);
 
 void aacenc_get_lib_info(LIB_INFO *info);
 
-int aacenc_mp4asc(const aacenc_param_t *params,
-                  const uint8_t *asc, uint32_t ascsize,
-                  uint8_t *outasc, uint32_t *outsize);
-
 int aacenc_init(HANDLE_AACENCODER *encoder, const aacenc_param_t *params,
                 const pcm_sample_description_t *format,
                 AACENC_InfoStruct *info);

src/main.c

@@ -785,15 +785,6 @@ int main(int argc, char **argv)
 
     sample_format = pcm_get_format(reader);
 
-    /*
-     * We use explicit/hierarchical signaling for LOAS.
-     * Other than that, we request implicit signaling to FDK library, then 
-     * append explicit/backward-compatible signaling to ASC in case of MP4FF.
-     *
-     * Explicit/backward-compatible signaling of SBR is the most recommended
-     * way in MPEG4 part3 spec, and seems the only way supported by iTunes.
-     * Since FDK library does not support it, we have to do it on our side.
-     */
     sbr_mode = aacenc_is_sbr_active((aacenc_param_t*)&params);
     if (sbr_mode && !aacenc_is_sbr_ratio_available()) {
         fprintf(stderr, "WARNING: Only dual-rate SBR is available "
@@ -801,7 +792,9 @@ int main(int argc, char **argv)
         params.sbr_ratio = 2;
     }
     scale_shift = aacenc_is_dual_rate_sbr((aacenc_param_t*)&params);
-    params.sbr_signaling = (params.transport_format == TT_MP4_LOAS) ? 2 : 0;
+    params.sbr_signaling =
+        (params.transport_format == TT_MP4_LOAS) ? 2 :
+        (params.transport_format == TT_MP4_RAW)  ? 1 : 0;
     if (sbr_mode && !scale_shift)
         params.sbr_signaling = 2;
 
@@ -824,16 +817,13 @@ int main(int argc, char **argv)
 
     if (!params.transport_format) {
         uint32_t scale;
-        uint8_t mp4asc[32];
-        uint32_t ascsize = sizeof(mp4asc);
         unsigned framelen = aacinfo.frameLength;
         scale = sample_format->sample_rate >> scale_shift;
         if ((m4af = m4af_create(M4AF_CODEC_MP4A, scale, &m4af_io,
                                 params.output_fp)) < 0)
             goto END;
-        aacenc_mp4asc((aacenc_param_t*)&params, aacinfo.confBuf,
-                      aacinfo.confSize, mp4asc, &ascsize);
-        m4af_set_decoder_specific_info(m4af, 0, mp4asc, ascsize);
+        m4af_set_decoder_specific_info(m4af, 0,
+                                       aacinfo.confBuf, aacinfo.confSize);
         m4af_set_fixed_frame_duration(m4af, 0,
                                       framelen >> scale_shift);
         m4af_set_vbr_mode(m4af, 0, params.bitrate_mode);