bmv: Split audio and video decoder

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

1 files changed, 293 insertions, 0 deletions

diff --git a/libavcodec/bmvvideo.c b/libavcodec/bmvvideo.c
new file mode 100644
index 0000000000..ebc8e7a082
--- /dev/null
+++ b/libavcodec/bmvvideo.c
@@ -0,0 +1,293 @@
+/*
+ * Discworld II BMV video 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/common.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "internal.h"
+
+enum BMVFlags{
+    BMV_NOP = 0,
+    BMV_END,
+    BMV_DELTA,
+    BMV_INTRA,
+
+    BMV_SCROLL  = 0x04,
+    BMV_PALETTE = 0x08,
+    BMV_COMMAND = 0x10,
+    BMV_AUDIO   = 0x20,
+    BMV_EXT     = 0x40,
+    BMV_PRINT   = 0x80
+};
+
+#define SCREEN_WIDE 640
+#define SCREEN_HIGH 429
+
+typedef struct BMVDecContext {
+    AVCodecContext *avctx;
+
+    uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
+    uint32_t pal[256];
+    const uint8_t *stream;
+} BMVDecContext;
+
+#define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
+
+static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
+{
+    unsigned val, saved_val = 0;
+    int tmplen = src_len;
+    const uint8_t *src, *source_end = source + src_len;
+    uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
+    uint8_t *dst, *dst_end;
+    int len, mask;
+    int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
+    int read_two_nibbles, flag;
+    int advance_mode;
+    int mode = 0;
+    int i;
+
+    if (src_len <= 0)
+        return AVERROR_INVALIDDATA;
+
+    if (forward) {
+        src = source;
+        dst = frame;
+        dst_end = frame_end;
+    } else {
+        src = source + src_len - 1;
+        dst = frame_end - 1;
+        dst_end = frame - 1;
+    }
+    for (;;) {
+        int shift = 0;
+        flag = 0;
+
+        /* The mode/len decoding is a bit strange:
+         * values are coded as variable-length codes with nibble units,
+         * code end is signalled by two top bits in the nibble being nonzero.
+         * And since data is bytepacked and we read two nibbles at a time,
+         * we may get a nibble belonging to the next code.
+         * Hence this convoluted loop.
+         */
+        if (!mode || (tmplen == 4)) {
+            if (src < source || src >= source_end)
+                return AVERROR_INVALIDDATA;
+            val = *src;
+            read_two_nibbles = 1;
+        } else {
+            val = saved_val;
+            read_two_nibbles = 0;
+        }
+        if (!(val & 0xC)) {
+            for (;;) {
+                if (!read_two_nibbles) {
+                    if (src < source || src >= source_end)
+                        return AVERROR_INVALIDDATA;
+                    shift += 2;
+                    val |= *src << shift;
+                    if (*src & 0xC)
+                        break;
+                }
+                // two upper bits of the nibble is zero,
+                // so shift top nibble value down into their place
+                read_two_nibbles = 0;
+                shift += 2;
+                mask = (1 << shift) - 1;
+                val = ((val >> 2) & ~mask) | (val & mask);
+                NEXT_BYTE(src);
+                if ((val & (0xC << shift))) {
+                    flag = 1;
+                    break;
+                }
+            }
+        } else if (mode) {
+            flag = tmplen != 4;
+        }
+        if (flag) {
+            tmplen = 4;
+        } else {
+            saved_val = val >> (4 + shift);
+            tmplen = 0;
+            val &= (1 << (shift + 4)) - 1;
+            NEXT_BYTE(src);
+        }
+        advance_mode = val & 1;
+        len = (val >> 1) - 1;
+        mode += 1 + advance_mode;
+        if (mode >= 4)
+            mode -= 3;
+        if (len <= 0 || FFABS(dst_end - dst) < len)
+            return AVERROR_INVALIDDATA;
+        switch (mode) {
+        case 1:
+            if (forward) {
+                if (dst - frame + SCREEN_WIDE < frame_off ||
+                        dst - frame + SCREEN_WIDE + frame_off < 0 ||
+                        frame_end - dst < frame_off + len ||
+                        frame_end - dst < len)
+                    return AVERROR_INVALIDDATA;
+                for (i = 0; i < len; i++)
+                    dst[i] = dst[frame_off + i];
+                dst += len;
+            } else {
+                dst -= len;
+                if (dst - frame + SCREEN_WIDE < frame_off ||
+                        dst - frame + SCREEN_WIDE + frame_off < 0 ||
+                        frame_end - dst < frame_off + len ||
+                        frame_end - dst < len)
+                    return AVERROR_INVALIDDATA;
+                for (i = len - 1; i >= 0; i--)
+                    dst[i] = dst[frame_off + i];
+            }
+            break;
+        case 2:
+            if (forward) {
+                if (source + src_len - src < len)
+                    return AVERROR_INVALIDDATA;
+                memcpy(dst, src, len);
+                dst += len;
+                src += len;
+            } else {
+                if (src - source < len)
+                    return AVERROR_INVALIDDATA;
+                dst -= len;
+                src -= len;
+                memcpy(dst, src, len);
+            }
+            break;
+        case 3:
+            val = forward ? dst[-1] : dst[1];
+            if (forward) {
+                memset(dst, val, len);
+                dst += len;
+            } else {
+                dst -= len;
+                memset(dst, val, len);
+            }
+            break;
+        default:
+            break;
+        }
+        if (dst == dst_end)
+            return 0;
+    }
+    return 0;
+}
+
+static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
+                        AVPacket *pkt)
+{
+    BMVDecContext * const c = avctx->priv_data;
+    AVFrame *frame = data;
+    int type, scr_off;
+    int i, ret;
+    uint8_t *srcptr, *outptr;
+
+    c->stream = pkt->data;
+    type = bytestream_get_byte(&c->stream);
+    if (type & BMV_AUDIO) {
+        int blobs = bytestream_get_byte(&c->stream);
+        if (pkt->size < blobs * 65 + 2) {
+            av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
+            return AVERROR_INVALIDDATA;
+        }
+        c->stream += blobs * 65;
+    }
+    if (type & BMV_COMMAND) {
+        int command_size = (type & BMV_PRINT) ? 8 : 10;
+        if (c->stream - pkt->data + command_size > pkt->size) {
+            av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
+            return AVERROR_INVALIDDATA;
+        }
+        c->stream += command_size;
+    }
+    if (type & BMV_PALETTE) {
+        if (c->stream - pkt->data > pkt->size - 768) {
+            av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
+            return AVERROR_INVALIDDATA;
+        }
+        for (i = 0; i < 256; i++)
+            c->pal[i] = bytestream_get_be24(&c->stream);
+    }
+    if (type & BMV_SCROLL) {
+        if (c->stream - pkt->data > pkt->size - 2) {
+            av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
+            return AVERROR_INVALIDDATA;
+        }
+        scr_off = (int16_t)bytestream_get_le16(&c->stream);
+    } else if ((type & BMV_INTRA) == BMV_INTRA) {
+        scr_off = -640;
+    } else {
+        scr_off = 0;
+    }
+
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return ret;
+    }
+
+    if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
+        av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
+    frame->palette_has_changed = type & BMV_PALETTE;
+
+    outptr = frame->data[0];
+    srcptr = c->frame;
+
+    for (i = 0; i < avctx->height; i++) {
+        memcpy(outptr, srcptr, avctx->width);
+        srcptr += avctx->width;
+        outptr += frame->linesize[0];
+    }
+
+    *got_frame = 1;
+
+    /* always report that the buffer was completely consumed */
+    return pkt->size;
+}
+
+static av_cold int decode_init(AVCodecContext *avctx)
+{
+    BMVDecContext * const c = avctx->priv_data;
+
+    c->avctx = avctx;
+    avctx->pix_fmt = AV_PIX_FMT_PAL8;
+
+    c->frame = c->frame_base + 640;
+
+    return 0;
+}
+
+AVCodec ff_bmv_video_decoder = {
+    .name           = "bmv_video",
+    .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_BMV_VIDEO,
+    .priv_data_size = sizeof(BMVDecContext),
+    .init           = decode_init,
+    .decode         = decode_frame,
+    .capabilities   = CODEC_CAP_DR1,
+};