bmv: Split audio and video decoder

Signed-off-by: Diego Biurrun <diego@biurrun.de>

1 files changed, 91 insertions, 0 deletions

diff --git a/libavcodec/bmvaudio.c b/libavcodec/bmvaudio.c
new file mode 100644
index 0000000..0f8c224
--- /dev/null
+++ b/libavcodec/bmvaudio.c
@@ -0,0 +1,91 @@
+/*
+ * Discworld II BMV audio decoder
+ * Copyright (c) 2011 Konstantin Shishkov
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/channel_layout.h"
+#include "libavutil/common.h"
+
+#include "avcodec.h"
+#include "internal.h"
+
+static const int bmv_aud_mults[16] = {
+    16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
+};
+
+static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
+{
+    avctx->channels       = 2;
+    avctx->channel_layout = AV_CH_LAYOUT_STEREO;
+    avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
+
+    return 0;
+}
+
+static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
+                                int *got_frame_ptr, AVPacket *avpkt)
+{
+    AVFrame *frame     = data;
+    const uint8_t *buf = avpkt->data;
+    int buf_size = avpkt->size;
+    int blocks = 0, total_blocks, i;
+    int ret;
+    int16_t *output_samples;
+    int scale[2];
+
+    total_blocks = *buf++;
+    if (buf_size < total_blocks * 65 + 1) {
+        av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
+               total_blocks * 65 + 1, buf_size);
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* get output buffer */
+    frame->nb_samples = total_blocks * 32;
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return ret;
+    }
+    output_samples = (int16_t *)frame->data[0];
+
+    for (blocks = 0; blocks < total_blocks; blocks++) {
+        uint8_t code = *buf++;
+        code = (code >> 1) | (code << 7);
+        scale[0] = bmv_aud_mults[code & 0xF];
+        scale[1] = bmv_aud_mults[code >> 4];
+        for (i = 0; i < 32; i++) {
+            *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
+            *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
+        }
+    }
+
+    *got_frame_ptr = 1;
+
+    return buf_size;
+}
+
+AVCodec ff_bmv_audio_decoder = {
+    .name           = "bmv_audio",
+    .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
+    .type           = AVMEDIA_TYPE_AUDIO,
+    .id             = AV_CODEC_ID_BMV_AUDIO,
+    .init           = bmv_aud_decode_init,
+    .decode         = bmv_aud_decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
+};