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-rw-r--r--media/ffvpx/libavcodec/mpegaudiodecheader.c152
1 files changed, 152 insertions, 0 deletions
diff --git a/media/ffvpx/libavcodec/mpegaudiodecheader.c b/media/ffvpx/libavcodec/mpegaudiodecheader.c
new file mode 100644
index 0000000000..ef63befbf4
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+++ b/media/ffvpx/libavcodec/mpegaudiodecheader.c
@@ -0,0 +1,152 @@
+/*
+ * MPEG Audio header decoder
+ * Copyright (c) 2001, 2002 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * MPEG Audio header decoder.
+ */
+
+#include "libavutil/macros.h"
+
+#include "mpegaudio.h"
+#include "mpegaudiodata.h"
+#include "mpegaudiodecheader.h"
+
+
+int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
+{
+ int sample_rate, frame_size, mpeg25, padding;
+ int sample_rate_index, bitrate_index;
+ int ret;
+
+ ret = ff_mpa_check_header(header);
+ if (ret < 0)
+ return ret;
+
+ if (header & (1<<20)) {
+ s->lsf = (header & (1<<19)) ? 0 : 1;
+ mpeg25 = 0;
+ } else {
+ s->lsf = 1;
+ mpeg25 = 1;
+ }
+
+ s->layer = 4 - ((header >> 17) & 3);
+ /* extract frequency */
+ sample_rate_index = (header >> 10) & 3;
+ if (sample_rate_index >= FF_ARRAY_ELEMS(ff_mpa_freq_tab))
+ sample_rate_index = 0;
+ sample_rate = ff_mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);
+ sample_rate_index += 3 * (s->lsf + mpeg25);
+ s->sample_rate_index = sample_rate_index;
+ s->error_protection = ((header >> 16) & 1) ^ 1;
+ s->sample_rate = sample_rate;
+
+ bitrate_index = (header >> 12) & 0xf;
+ padding = (header >> 9) & 1;
+ //extension = (header >> 8) & 1;
+ s->mode = (header >> 6) & 3;
+ s->mode_ext = (header >> 4) & 3;
+ //copyright = (header >> 3) & 1;
+ //original = (header >> 2) & 1;
+ //emphasis = header & 3;
+
+ if (s->mode == MPA_MONO)
+ s->nb_channels = 1;
+ else
+ s->nb_channels = 2;
+
+ if (bitrate_index != 0) {
+ frame_size = ff_mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];
+ s->bit_rate = frame_size * 1000;
+ switch(s->layer) {
+ case 1:
+ frame_size = (frame_size * 12000) / sample_rate;
+ frame_size = (frame_size + padding) * 4;
+ break;
+ case 2:
+ frame_size = (frame_size * 144000) / sample_rate;
+ frame_size += padding;
+ break;
+ default:
+ case 3:
+ frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
+ frame_size += padding;
+ break;
+ }
+ s->frame_size = frame_size;
+ } else {
+ /* if no frame size computed, signal it */
+ return 1;
+ }
+
+#if defined(DEBUG)
+ ff_dlog(NULL, "layer%d, %d Hz, %d kbits/s, ",
+ s->layer, s->sample_rate, s->bit_rate);
+ if (s->nb_channels == 2) {
+ if (s->layer == 3) {
+ if (s->mode_ext & MODE_EXT_MS_STEREO)
+ ff_dlog(NULL, "ms-");
+ if (s->mode_ext & MODE_EXT_I_STEREO)
+ ff_dlog(NULL, "i-");
+ }
+ ff_dlog(NULL, "stereo");
+ } else {
+ ff_dlog(NULL, "mono");
+ }
+ ff_dlog(NULL, "\n");
+#endif
+ return 0;
+}
+
+int ff_mpa_decode_header(uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate, enum AVCodecID *codec_id)
+{
+ MPADecodeHeader s1, *s = &s1;
+
+ if (avpriv_mpegaudio_decode_header(s, head) != 0) {
+ return -1;
+ }
+
+ switch(s->layer) {
+ case 1:
+ *codec_id = AV_CODEC_ID_MP1;
+ *frame_size = 384;
+ break;
+ case 2:
+ *codec_id = AV_CODEC_ID_MP2;
+ *frame_size = 1152;
+ break;
+ default:
+ case 3:
+ if (*codec_id != AV_CODEC_ID_MP3ADU)
+ *codec_id = AV_CODEC_ID_MP3;
+ if (s->lsf)
+ *frame_size = 576;
+ else
+ *frame_size = 1152;
+ break;
+ }
+
+ *sample_rate = s->sample_rate;
+ *channels = s->nb_channels;
+ *bit_rate = s->bit_rate;
+ return s->frame_size;
+}