avcodec/dca: use LUT for LBR frequency ranges

Values for unsupported frequencies > 48000 Hz are still included (parser
will make use of them).

Also convert sampling frequencies array to unsigned.

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/dca_lbr.c

@@ -1000,15 +1000,15 @@ static int parse_decoder_init(DCALbrDecoder *s, GetByteContext *gb)
     int old_band_limit = s->band_limit;
     int old_nchannels = s->nchannels;
     int version, bit_rate_hi;
-    unsigned int code;
+    unsigned int sr_code;
 
     // Sample rate of LBR audio
-    code = bytestream2_get_byte(gb);
-    if (code >= FF_ARRAY_ELEMS(ff_dca_sampling_freqs)) {
+    sr_code = bytestream2_get_byte(gb);
+    if (sr_code >= FF_ARRAY_ELEMS(ff_dca_sampling_freqs)) {
         av_log(s->avctx, AV_LOG_ERROR, "Invalid LBR sample rate\n");
         return AVERROR_INVALIDDATA;
     }
-    s->sample_rate = ff_dca_sampling_freqs[code];
+    s->sample_rate = ff_dca_sampling_freqs[sr_code];
     if (s->sample_rate > 48000) {
         avpriv_report_missing_feature(s->avctx, "%d Hz LBR sample rate", s->sample_rate);
         return AVERROR_PATCHWELCOME;
@@ -1076,12 +1076,7 @@ static int parse_decoder_init(DCALbrDecoder *s, GetByteContext *gb)
     }
 
     // Setup frequency range
-    if (s->sample_rate < 14000)
-        s->freq_range = 0;
-    else if (s->sample_rate < 28000)
-        s->freq_range = 1;
-    else
-        s->freq_range = 2;
+    s->freq_range = ff_dca_freq_ranges[sr_code];
 
     // Setup resolution profile
     if (s->bit_rate_orig >= 44000 * (s->nchannels_total + 2))

libavcodec/dcadata.c

@@ -8725,11 +8725,15 @@ const int32_t ff_dca_xll_band_coeff[20] = {
      3259333, -5074941,  6928550, -8204883
 };
 
-const int32_t ff_dca_sampling_freqs[16] = {
+const uint32_t ff_dca_sampling_freqs[16] = {
       8000,  16000, 32000, 64000, 128000, 22050,  44100,  88200,
     176400, 352800, 12000, 24000,  48000, 96000, 192000, 384000,
 };
 
+const uint8_t ff_dca_freq_ranges[16] = {
+    0, 1, 2, 3, 4, 1, 2, 3, 4, 4, 0, 1, 2, 3, 4, 4
+};
+
 const uint16_t ff_dca_avg_g3_freqs[3] = { 16000, 18000, 24000 };
 
 const uint16_t ff_dca_fst_amp[44] = {

libavcodec/dcadata.h

@@ -71,7 +71,8 @@ extern const uint16_t ff_dca_xll_refl_coeff[128];
 
 extern const int32_t ff_dca_xll_band_coeff[20];
 
-extern const int32_t ff_dca_sampling_freqs[16];
+extern const uint32_t ff_dca_sampling_freqs[16];
+extern const uint8_t ff_dca_freq_ranges[16];
 
 extern const uint16_t ff_dca_avg_g3_freqs[3];