* add support for liba52

Originally committed as revision 411 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 251 insertions, 0 deletions

diff --git a/libavcodec/a52dec.c b/libavcodec/a52dec.c
new file mode 100644
index 0000000000..419ce05240
--- /dev/null
+++ b/libavcodec/a52dec.c
@@ -0,0 +1,251 @@
+/*
+ * A52 decoder
+ * Copyright (c) 2001 Gerard Lantau.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include "avcodec.h"
+#include "liba52/a52.h"
+
+#ifdef LIBAVCODEC_A52BIN
+#include <dlfcn.h>
+static const char* liba52name = "liba52.so.0";
+#endif
+
+/**
+ * liba52 - Copyright (C) Aaron Holtzman
+ * released under the GPL license.
+ */
+typedef struct AC3DecodeState {
+    UINT8 inbuf[4096]; /* input buffer */
+    UINT8 *inbuf_ptr;
+    int frame_size;
+    int flags;
+    int channels;
+    a52_state_t* state;
+    sample_t* samples;
+
+    /*
+     * virtual method table
+     *
+     * using this function table so the liba52 doesn't
+     * have to be really linked together with ffmpeg
+     * and might be linked in runtime - this allows binary
+     * distribution of ffmpeg library which doens't depend
+     * on liba52 library - but if user has it installed
+     * it will be used - user might install such library
+     * separately
+     */
+    void* handle;
+    a52_state_t* (*a52_init)(uint32_t mm_accel);
+    sample_t* (*a52_samples)(a52_state_t * state);
+    int (*a52_syncinfo)(uint8_t * buf, int * flags,
+			  int * sample_rate, int * bit_rate);
+    int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
+		       sample_t * level, sample_t bias);
+    void (*a52_dynrng)(a52_state_t * state,
+			 sample_t (* call) (sample_t, void *), void * data);
+    int (*a52_block)(a52_state_t * state);
+    void (*a52_free)(a52_state_t * state);
+
+} AC3DecodeState;
+
+#ifdef LIBAVCODEC_A52BIN
+static void* dlsymm(void* handle, const char* symbol)
+{
+    void* f = dlsym(handle, symbol);
+    if (!f)
+	fprintf(stderr, "A52 Decoder - function '%s' can't be resolved\n", symbol);
+    return f;
+}
+#endif
+
+static int a52_decode_init(AVCodecContext *avctx)
+{
+    AC3DecodeState *s = avctx->priv_data;
+
+#ifdef LIBAVCODEC_A52BIN
+    s->handle = dlopen(liba52name, RTLD_LAZY);
+    if (!s->handle)
+    {
+	fprintf(stderr, "A52 library %s  could not be opened: %s\n", liba52name, dlerror());
+        return -1;
+    }
+    s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
+    s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
+    s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
+    s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
+    s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
+    s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
+    if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
+        || !s->a52_frame || !s->a52_block || !s->a52_free)
+    {
+	dlclose(s->handle);
+        return -1;
+    }
+    printf("INITIALIZED\n");
+#else
+    /* static linked version */
+    s->handle = 0;
+    s->a52_init = a52_init;
+    s->a52_samples = a52_samples;
+    s->a52_syncinfo = a52_syncinfo;
+    s->a52_frame = a52_frame;
+    s->a52_block = a52_block;
+    s->a52_free = a52_free;
+#endif
+    s->state = s->a52_init(0); /* later use CPU flags */
+    s->samples = s->a52_samples(s->state);
+    s->inbuf_ptr = s->inbuf;
+    s->frame_size = 0;
+
+    return 0;
+}
+
+/**** the following two functions comes from a52dec */
+static inline int blah (int32_t i)
+{
+    if (i > 0x43c07fff)
+	return 32767;
+    else if (i < 0x43bf8000)
+	return -32768;
+    return i - 0x43c00000;
+}
+
+static inline void float_to_int (float * _f, INT16 * s16, int nchannels)
+{
+    int i, j, c;
+    int32_t * f = (int32_t *) _f;	// XXX assumes IEEE float format
+
+    j = 0;
+    nchannels *= 256;
+    for (i = 0; i < 256; i++) {
+	for (c = 0; c < nchannels; c += 256)
+	    s16[j++] = blah (f[i + c]);
+    }
+}
+
+/**** end */
+
+#define HEADER_SIZE 7
+
+static int a52_decode_frame(AVCodecContext *avctx,
+                            void *data, int *data_size,
+                            UINT8 *buf, int buf_size)
+{
+    AC3DecodeState *s = avctx->priv_data;
+    UINT8 *buf_ptr;
+    int flags, i, len;
+    int sample_rate, bit_rate;
+    short *out_samples = data;
+    float level;
+    static const int ac3_channels[8] = {
+	2, 1, 2, 3, 3, 4, 4, 5
+    };
+
+    *data_size = 0;
+    buf_ptr = buf;
+    while (buf_size > 0) {
+        len = s->inbuf_ptr - s->inbuf;
+        if (s->frame_size == 0) {
+            /* no header seen : find one. We need at least 7 bytes to parse it */
+            len = HEADER_SIZE - len;
+            if (len > buf_size)
+                len = buf_size;
+            memcpy(s->inbuf_ptr, buf_ptr, len);
+            buf_ptr += len;
+            s->inbuf_ptr += len;
+            buf_size -= len;
+            if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
+                len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
+                if (len == 0) {
+                    /* no sync found : move by one byte (inefficient, but simple!) */
+                    memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
+                    s->inbuf_ptr--;
+                } else {
+		    s->frame_size = len;
+                    /* update codec info */
+                    avctx->sample_rate = sample_rate;
+                    s->channels = ac3_channels[s->flags & 7];
+                    if (s->flags & A52_LFE)
+			s->channels++;
+		    if (avctx->channels == 0)
+			/* No specific number of channel requested */
+			avctx->channels = s->channels;
+		    else if (s->channels < avctx->channels) {
+			fprintf(stderr, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
+			avctx->channels = s->channels;
+		    }
+		    avctx->bit_rate = bit_rate;
+                }
+            }
+        } else if (len < s->frame_size) {
+            len = s->frame_size - len;
+            if (len > buf_size)
+                len = buf_size;
+
+            memcpy(s->inbuf_ptr, buf_ptr, len);
+            buf_ptr += len;
+            s->inbuf_ptr += len;
+            buf_size -= len;
+        } else {
+            flags = s->flags;
+            if (avctx->channels == 1)
+                flags = A52_MONO;
+            else if (avctx->channels == 2)
+                flags = A52_STEREO;
+            else
+                flags |= A52_ADJUST_LEVEL;
+            level = 1;
+            if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
+            fail:
+                s->inbuf_ptr = s->inbuf;
+                s->frame_size = 0;
+                continue;
+            }
+            for (i = 0; i < 6; i++) {
+                if (s->a52_block(s->state))
+                    goto fail;
+                float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
+            }
+            s->inbuf_ptr = s->inbuf;
+            s->frame_size = 0;
+            *data_size = 6 * avctx->channels * 256 * sizeof(INT16);
+            break;
+        }
+    }
+    return buf_ptr - buf;
+}
+
+static int a52_decode_end(AVCodecContext *avctx)
+{
+    AC3DecodeState *s = avctx->priv_data;
+    s->a52_free(s->state);
+#ifdef LIBAVCODEC_A52BIN
+    dlclose(s->handle);
+#endif
+    return 0;
+}
+
+AVCodec ac3_decoder = {
+    "ac3",
+    CODEC_TYPE_AUDIO,
+    CODEC_ID_AC3,
+    sizeof(AC3DecodeState),
+    a52_decode_init,
+    NULL,
+    a52_decode_end,
+    a52_decode_frame,
+};