VBLE Decoder

Add a decoder for the VBLE Lossless Codec, which
still has a cult following. Used to be popular
several years ago on doom9.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Martin Storsjö <martin@martin.st>

1 files changed, 248 insertions, 0 deletions

diff --git a/libavcodec/vble.c b/libavcodec/vble.c
new file mode 100644
index 0000000000..436402ded4
--- /dev/null
+++ b/libavcodec/vble.c
@@ -0,0 +1,248 @@
+/*
+ * VBLE Decoder
+ * Copyright (c) 2011 Derek Buitenhuis
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * VBLE Decoder
+ */
+
+#define ALT_BITSTREAM_READER_LE
+
+#include "avcodec.h"
+#include "get_bits.h"
+
+typedef struct {
+    AVCodecContext *avctx;
+
+    int            size;
+    int            flags;
+    uint8_t        *len;
+    uint8_t        *val;
+} VBLEContext;
+
+static uint8_t vble_read_reverse_unary(GetBitContext *gb)
+{
+    /* At most we need to read 9 bits total to get indices up to 8 */
+    uint8_t val = show_bits(gb, 8);
+
+    if (val) {
+        val = 7 - av_log2_16bit(av_reverse[val]);
+        skip_bits(gb, val + 1);
+        return val;
+    } else {
+        skip_bits(gb, 8);
+        if (get_bits1(gb))
+            return 8;
+    }
+
+    /* Return something larger than 8 on error */
+    return UINT8_MAX;
+}
+
+static int vble_unpack(VBLEContext *ctx, GetBitContext *gb)
+{
+    int i;
+
+    /* Read all the lengths in first */
+    for (i = 0; i < ctx->size; i++) {
+        ctx->len[i] = vble_read_reverse_unary(gb);
+
+        if (ctx->len[i] == UINT8_MAX)
+            return -1;
+    }
+
+    /* For any values that have length 0 */
+    memset(ctx->val, 0, ctx->size);
+
+    for (i = 0; i < ctx->size; i++) {
+        /* Check we have enough bits left */
+        if (get_bits_left(gb) < ctx->len[i])
+            return -1;
+
+        /* get_bits can't take a length of 0 */
+        if (ctx->len[i])
+            ctx->val[i] = (1 << ctx->len[i]) + get_bits(gb, ctx->len[i]) - 1;
+    }
+
+    return 0;
+}
+
+static void vble_restore_plane(VBLEContext *ctx, int plane, int offset,
+                              int width, int height)
+{
+    AVFrame *pic = ctx->avctx->coded_frame;
+    uint8_t *dst = pic->data[plane];
+    uint8_t *val = ctx->val + offset;
+    uint8_t *len = ctx->len + offset;
+    uint8_t a, b, c;
+    int stride = pic->linesize[plane];
+    int i, j;
+
+    for (i = 0; i < height; i++) {
+        for (j = 0; j < width; j++) {
+            dst[j] = (val[j] >> 1) ^ -(val[j] & 1);
+
+            /* Top line and left column are not predicted */
+            if (!j)
+                continue;
+
+            if (!i) {
+                dst[j] += dst[j - 1];
+                continue;
+            }
+
+            a = dst[j - 1];
+            b = dst[j - stride];
+            c = a + b - dst[j - 1 - stride];
+            dst[j] += mid_pred(a, b, c);
+        }
+        dst += stride;
+        val += width;
+        len += width;
+    }
+}
+
+static int vble_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
+                             AVPacket *avpkt)
+{
+    VBLEContext *ctx = avctx->priv_data;
+    AVFrame *pic = avctx->coded_frame;
+    GetBitContext gb;
+    const uint8_t *src = avpkt->data;
+    int version;
+    int offset = 0;
+    int width_uv = avctx->width / 2, height_uv = avctx->height / 2;
+
+    pic->reference = 0;
+
+    /* Clear buffer if need be */
+    if (pic->data[0])
+        avctx->release_buffer(avctx, pic);
+
+    /* Allocate buffer */
+    if (avctx->get_buffer(avctx, pic) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Could not allocate buffer.\n");
+        return AVERROR(ENOMEM);
+    }
+
+    /* Set flags */
+    pic->key_frame = 1;
+    pic->pict_type = FF_I_TYPE;
+
+    /* Version should always be 1 */
+    version = AV_RL32(src);
+
+    if (version != 1) {
+        av_log(avctx, AV_LOG_ERROR, "Unsupported VBLE Version: %d\n", version);
+        return AVERROR_INVALIDDATA;
+    }
+
+    init_get_bits(&gb, src + 4, (avpkt->size - 4) * 8);
+
+    /* Unpack */
+    if (vble_unpack(ctx, &gb) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid Code\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    /* Restore planes. Should be almost identical to Huffyuv's. */
+    vble_restore_plane(ctx, 0, offset, avctx->width, avctx->height);
+
+    /* Chroma */
+    if (!(ctx->flags & CODEC_FLAG_GRAY)) {
+        offset += avctx->width * avctx->height;
+        vble_restore_plane(ctx, 1, offset, width_uv, height_uv);
+
+        offset += width_uv * height_uv;
+        vble_restore_plane(ctx, 2, offset, width_uv, height_uv);
+    }
+
+    *data_size = sizeof(AVFrame);
+    *(AVFrame *)data = *pic;
+
+    return avpkt->size;
+}
+
+static av_cold int vble_decode_close(AVCodecContext *avctx)
+{
+    VBLEContext *ctx = avctx->priv_data;
+    AVFrame *pic = avctx->coded_frame;
+
+    if (pic->data[0])
+        avctx->release_buffer(avctx, pic);
+
+    av_freep(&avctx->coded_frame);
+    av_freep(&ctx->len);
+    av_freep(&ctx->val);
+
+    return 0;
+}
+
+static av_always_inline int vble_error_close(AVCodecContext *avctx,
+                                             const char *message)
+{
+    av_log(avctx, AV_LOG_ERROR, message);
+    vble_decode_close(avctx);
+    return AVERROR(ENOMEM);
+}
+
+static av_cold int vble_decode_init(AVCodecContext *avctx)
+{
+    VBLEContext *ctx = avctx->priv_data;
+
+    /* Stash for later use */
+    ctx->avctx = avctx;
+    ctx->flags = avctx->flags;
+
+    avctx->pix_fmt = PIX_FMT_YUV420P;
+    avctx->bits_per_raw_sample = 8;
+    avctx->coded_frame = avcodec_alloc_frame();
+
+    if (!avctx->coded_frame)
+        return vble_error_close(avctx, "Could not allocate frame.\n");
+
+    ctx->size = avpicture_get_size(avctx->pix_fmt,
+                                   avctx->width, avctx->height);
+
+    ctx->len = av_malloc(ctx->size * sizeof(*ctx->len));
+
+    if (!ctx->len)
+        return vble_error_close(avctx, "Could not allocate lengths buffer.\n");
+
+    ctx->val = av_malloc(ctx->size * sizeof(*ctx->val));
+
+    if (!ctx->val)
+        return vble_error_close(avctx, "Could not allocate values buffer.\n");
+
+    return 0;
+}
+
+AVCodec ff_vble_decoder = {
+    .name           = "vble",
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = CODEC_ID_VBLE,
+    .priv_data_size = sizeof(VBLEContext),
+    .init           = vble_decode_init,
+    .close          = vble_decode_close,
+    .decode         = vble_decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
+    .long_name      = NULL_IF_CONFIG_SMALL("VBLE Lossless Codec"),
+};