Move decode_frame_header() from flacdec.c to flac.c/h to share with the

forthcoming FLAC parser.
Patch by Michael Chinen [mchinen at gmail]

Originally committed as revision 25909 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/flac.c

@@ -19,7 +19,101 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/crc.h"
 #include "flac.h"
+#include "flacdata.h"
+
+static const int8_t sample_size_table[] = { 0, 8, 12, 0, 16, 20, 24, 0 };
+
+static int64_t get_utf8(GetBitContext *gb)
+{
+    int64_t val;
+    GET_UTF8(val, get_bits(gb, 8), return -1;)
+    return val;
+}
+
+int ff_flac_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,
+                                FLACFrameInfo *fi)
+{
+    int bs_code, sr_code, bps_code;
+
+    /* frame sync code */
+    skip_bits(gb, 16);
+
+    /* block size and sample rate codes */
+    bs_code = get_bits(gb, 4);
+    sr_code = get_bits(gb, 4);
+
+    /* channels and decorrelation */
+    fi->ch_mode = get_bits(gb, 4);
+    if (fi->ch_mode < FLAC_MAX_CHANNELS) {
+        fi->channels = fi->ch_mode + 1;
+        fi->ch_mode = FLAC_CHMODE_INDEPENDENT;
+    } else if (fi->ch_mode <= FLAC_CHMODE_MID_SIDE) {
+        fi->channels = 2;
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", fi->ch_mode);
+        return -1;
+    }
+
+    /* bits per sample */
+    bps_code = get_bits(gb, 3);
+    if (bps_code == 3 || bps_code == 7) {
+        av_log(avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
+               bps_code);
+        return -1;
+    }
+    fi->bps = sample_size_table[bps_code];
+
+    /* reserved bit */
+    if (get_bits1(gb)) {
+        av_log(avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
+        return -1;
+    }
+
+    /* sample or frame count */
+    if (get_utf8(gb) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "utf8 fscked\n");
+        return -1;
+    }
+
+    /* blocksize */
+    if (bs_code == 0) {
+        av_log(avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
+        return -1;
+    } else if (bs_code == 6) {
+        fi->blocksize = get_bits(gb, 8) + 1;
+    } else if (bs_code == 7) {
+        fi->blocksize = get_bits(gb, 16) + 1;
+    } else {
+        fi->blocksize = ff_flac_blocksize_table[bs_code];
+    }
+
+    /* sample rate */
+    if (sr_code < 12) {
+        fi->samplerate = ff_flac_sample_rate_table[sr_code];
+    } else if (sr_code == 12) {
+        fi->samplerate = get_bits(gb, 8) * 1000;
+    } else if (sr_code == 13) {
+        fi->samplerate = get_bits(gb, 16);
+    } else if (sr_code == 14) {
+        fi->samplerate = get_bits(gb, 16) * 10;
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
+               sr_code);
+        return -1;
+    }
+
+    /* header CRC-8 check */
+    skip_bits(gb, 8);
+    if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
+               get_bits_count(gb)/8)) {
+        av_log(avctx, AV_LOG_ERROR, "header crc mismatch\n");
+        return -1;
+    }
+
+    return 0;
+}
 
 int ff_flac_get_max_frame_size(int blocksize, int ch, int bps)
 {

libavcodec/flac.h

@@ -28,6 +28,7 @@
 #define AVCODEC_FLAC_H
 
 #include "avcodec.h"
+#include "get_bits.h"
 
 #define FLAC_STREAMINFO_SIZE   34
 #define FLAC_MAX_CHANNELS       8
@@ -120,4 +121,13 @@ void ff_flac_parse_block_header(const uint8_t *block_header,
  */
 int ff_flac_get_max_frame_size(int blocksize, int ch, int bps);
 
+/**
+ * Validate and decode a frame header.
+ * @param      avctx AVCodecContext to use as av_log() context
+ * @param      gb    GetBitContext from which to read frame header
+ * @param[out] fi    frame information
+ * @return non-zero on error, 0 if ok
+ */
+int ff_flac_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,
+                                FLACFrameInfo *fi);
 #endif /* AVCODEC_FLAC_H */

libavcodec/flacdec.c

@@ -67,16 +67,6 @@ typedef struct FLACContext {
     unsigned int allocated_bitstream_size;
 } FLACContext;
 
-static const int sample_size_table[] =
-{ 0, 8, 12, 0, 16, 20, 24, 0 };
-
-static int64_t get_utf8(GetBitContext *gb)
-{
-    int64_t val;
-    GET_UTF8(val, get_bits(gb, 8), return -1;)
-    return val;
-}
-
 static void allocate_buffers(FLACContext *s);
 
 int ff_flac_is_extradata_valid(AVCodecContext *avctx,
@@ -480,103 +470,13 @@ static inline int decode_subframe(FLACContext *s, int channel)
     return 0;
 }
 
-/**
- * Validate and decode a frame header.
- * @param      avctx AVCodecContext to use as av_log() context
- * @param      gb    GetBitContext from which to read frame header
- * @param[out] fi    frame information
- * @return non-zero on error, 0 if ok
- */
-static int decode_frame_header(AVCodecContext *avctx, GetBitContext *gb,
-                               FLACFrameInfo *fi)
-{
-    int bs_code, sr_code, bps_code;
-
-    /* frame sync code */
-    skip_bits(gb, 16);
-
-    /* block size and sample rate codes */
-    bs_code = get_bits(gb, 4);
-    sr_code = get_bits(gb, 4);
-
-    /* channels and decorrelation */
-    fi->ch_mode = get_bits(gb, 4);
-    if (fi->ch_mode < FLAC_MAX_CHANNELS) {
-        fi->channels = fi->ch_mode + 1;
-        fi->ch_mode = FLAC_CHMODE_INDEPENDENT;
-    } else if (fi->ch_mode <= FLAC_CHMODE_MID_SIDE) {
-        fi->channels = 2;
-    } else {
-        av_log(avctx, AV_LOG_ERROR, "invalid channel mode: %d\n", fi->ch_mode);
-        return -1;
-    }
-
-    /* bits per sample */
-    bps_code = get_bits(gb, 3);
-    if (bps_code == 3 || bps_code == 7) {
-        av_log(avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
-               bps_code);
-        return -1;
-    }
-    fi->bps = sample_size_table[bps_code];
-
-    /* reserved bit */
-    if (get_bits1(gb)) {
-        av_log(avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
-        return -1;
-    }
-
-    /* sample or frame count */
-    if (get_utf8(gb) < 0) {
-        av_log(avctx, AV_LOG_ERROR, "utf8 fscked\n");
-        return -1;
-    }
-
-    /* blocksize */
-    if (bs_code == 0) {
-        av_log(avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
-        return -1;
-    } else if (bs_code == 6) {
-        fi->blocksize = get_bits(gb, 8) + 1;
-    } else if (bs_code == 7) {
-        fi->blocksize = get_bits(gb, 16) + 1;
-    } else {
-        fi->blocksize = ff_flac_blocksize_table[bs_code];
-    }
-
-    /* sample rate */
-    if (sr_code < 12) {
-        fi->samplerate = ff_flac_sample_rate_table[sr_code];
-    } else if (sr_code == 12) {
-        fi->samplerate = get_bits(gb, 8) * 1000;
-    } else if (sr_code == 13) {
-        fi->samplerate = get_bits(gb, 16);
-    } else if (sr_code == 14) {
-        fi->samplerate = get_bits(gb, 16) * 10;
-    } else {
-        av_log(avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
-               sr_code);
-        return -1;
-    }
-
-    /* header CRC-8 check */
-    skip_bits(gb, 8);
-    if (av_crc(av_crc_get_table(AV_CRC_8_ATM), 0, gb->buffer,
-               get_bits_count(gb)/8)) {
-        av_log(avctx, AV_LOG_ERROR, "header crc mismatch\n");
-        return -1;
-    }
-
-    return 0;
-}
-
 static int decode_frame(FLACContext *s)
 {
     int i;
     GetBitContext *gb = &s->gb;
     FLACFrameInfo fi;
 
-    if (decode_frame_header(s->avctx, gb, &fi)) {
+    if (ff_flac_decode_frame_header(s->avctx, gb, &fi)) {
         av_log(s->avctx, AV_LOG_ERROR, "invalid frame header\n");
         return -1;
     }