yading@10: /*
yading@10:  * Discworld II BMV video and audio decoder
yading@10:  * Copyright (c) 2011 Konstantin Shishkov
yading@10:  *
yading@10:  * This file is part of Libav.
yading@10:  *
yading@10:  * Libav is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * Libav is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with Libav; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "libavutil/avassert.h"
yading@10: #include "libavutil/channel_layout.h"
yading@10: #include "avcodec.h"
yading@10: #include "bytestream.h"
yading@10: #include "internal.h"
yading@10: 
yading@10: enum BMVFlags{
yading@10:     BMV_NOP = 0,
yading@10:     BMV_END,
yading@10:     BMV_DELTA,
yading@10:     BMV_INTRA,
yading@10: 
yading@10:     BMV_SCROLL  = 0x04,
yading@10:     BMV_PALETTE = 0x08,
yading@10:     BMV_COMMAND = 0x10,
yading@10:     BMV_AUDIO   = 0x20,
yading@10:     BMV_EXT     = 0x40,
yading@10:     BMV_PRINT   = 0x80
yading@10: };
yading@10: 
yading@10: #define SCREEN_WIDE 640
yading@10: #define SCREEN_HIGH 429
yading@10: 
yading@10: typedef struct BMVDecContext {
yading@10:     AVCodecContext *avctx;
yading@10: 
yading@10:     uint8_t *frame, frame_base[SCREEN_WIDE * (SCREEN_HIGH + 1)];
yading@10:     uint32_t pal[256];
yading@10:     const uint8_t *stream;
yading@10: } BMVDecContext;
yading@10: 
yading@10: #define NEXT_BYTE(v) v = forward ? v + 1 : v - 1;
yading@10: 
yading@10: static int decode_bmv_frame(const uint8_t *source, int src_len, uint8_t *frame, int frame_off)
yading@10: {
yading@10:     unsigned val, saved_val = 0;
yading@10:     int tmplen = src_len;
yading@10:     const uint8_t *src, *source_end = source + src_len;
yading@10:     uint8_t *frame_end = frame + SCREEN_WIDE * SCREEN_HIGH;
yading@10:     uint8_t *dst, *dst_end;
yading@10:     int len, mask;
yading@10:     int forward = (frame_off <= -SCREEN_WIDE) || (frame_off >= 0);
yading@10:     int read_two_nibbles, flag;
yading@10:     int advance_mode;
yading@10:     int mode = 0;
yading@10:     int i;
yading@10: 
yading@10:     if (src_len <= 0)
yading@10:         return AVERROR_INVALIDDATA;
yading@10: 
yading@10:     if (forward) {
yading@10:         src = source;
yading@10:         dst = frame;
yading@10:         dst_end = frame_end;
yading@10:     } else {
yading@10:         src = source + src_len - 1;
yading@10:         dst = frame_end - 1;
yading@10:         dst_end = frame - 1;
yading@10:     }
yading@10:     for (;;) {
yading@10:         int shift = 0;
yading@10:         flag = 0;
yading@10: 
yading@10:         /* The mode/len decoding is a bit strange:
yading@10:          * values are coded as variable-length codes with nibble units,
yading@10:          * code end is signalled by two top bits in the nibble being nonzero.
yading@10:          * And since data is bytepacked and we read two nibbles at a time,
yading@10:          * we may get a nibble belonging to the next code.
yading@10:          * Hence this convoluted loop.
yading@10:          */
yading@10:         if (!mode || (tmplen == 4)) {
yading@10:             if (src < source || src >= source_end)
yading@10:                 return AVERROR_INVALIDDATA;
yading@10:             val = *src;
yading@10:             read_two_nibbles = 1;
yading@10:         } else {
yading@10:             val = saved_val;
yading@10:             read_two_nibbles = 0;
yading@10:         }
yading@10:         if (!(val & 0xC)) {
yading@10:             for (;;) {
yading@10:                 if(shift>22)
yading@10:                     return -1;
yading@10:                 if (!read_two_nibbles) {
yading@10:                     if (src < source || src >= source_end)
yading@10:                         return AVERROR_INVALIDDATA;
yading@10:                     shift += 2;
yading@10:                     val |= *src << shift;
yading@10:                     if (*src & 0xC)
yading@10:                         break;
yading@10:                 }
yading@10:                 // two upper bits of the nibble is zero,
yading@10:                 // so shift top nibble value down into their place
yading@10:                 read_two_nibbles = 0;
yading@10:                 shift += 2;
yading@10:                 mask = (1 << shift) - 1;
yading@10:                 val = ((val >> 2) & ~mask) | (val & mask);
yading@10:                 NEXT_BYTE(src);
yading@10:                 if ((val & (0xC << shift))) {
yading@10:                     flag = 1;
yading@10:                     break;
yading@10:                 }
yading@10:             }
yading@10:         } else if (mode) {
yading@10:             flag = tmplen != 4;
yading@10:         }
yading@10:         if (flag) {
yading@10:             tmplen = 4;
yading@10:         } else {
yading@10:             saved_val = val >> (4 + shift);
yading@10:             tmplen = 0;
yading@10:             val &= (1 << (shift + 4)) - 1;
yading@10:             NEXT_BYTE(src);
yading@10:         }
yading@10:         advance_mode = val & 1;
yading@10:         len = (val >> 1) - 1;
yading@10:         av_assert0(len>0);
yading@10:         mode += 1 + advance_mode;
yading@10:         if (mode >= 4)
yading@10:             mode -= 3;
yading@10:         if (len <= 0 || FFABS(dst_end - dst) < len)
yading@10:             return AVERROR_INVALIDDATA;
yading@10:         switch (mode) {
yading@10:         case 1:
yading@10:             if (forward) {
yading@10:                 if (dst - frame + SCREEN_WIDE < frame_off ||
yading@10:                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
yading@10:                         frame_end - dst < frame_off + len ||
yading@10:                         frame_end - dst < len)
yading@10:                     return AVERROR_INVALIDDATA;
yading@10:                 for (i = 0; i < len; i++)
yading@10:                     dst[i] = dst[frame_off + i];
yading@10:                 dst += len;
yading@10:             } else {
yading@10:                 dst -= len;
yading@10:                 if (dst - frame + SCREEN_WIDE < frame_off ||
yading@10:                         dst - frame + SCREEN_WIDE + frame_off < 0 ||
yading@10:                         frame_end - dst < frame_off + len ||
yading@10:                         frame_end - dst < len)
yading@10:                     return AVERROR_INVALIDDATA;
yading@10:                 for (i = len - 1; i >= 0; i--)
yading@10:                     dst[i] = dst[frame_off + i];
yading@10:             }
yading@10:             break;
yading@10:         case 2:
yading@10:             if (forward) {
yading@10:                 if (source + src_len - src < len)
yading@10:                     return AVERROR_INVALIDDATA;
yading@10:                 memcpy(dst, src, len);
yading@10:                 dst += len;
yading@10:                 src += len;
yading@10:             } else {
yading@10:                 if (src - source < len)
yading@10:                     return AVERROR_INVALIDDATA;
yading@10:                 dst -= len;
yading@10:                 src -= len;
yading@10:                 memcpy(dst, src, len);
yading@10:             }
yading@10:             break;
yading@10:         case 3:
yading@10:             val = forward ? dst[-1] : dst[1];
yading@10:             if (forward) {
yading@10:                 memset(dst, val, len);
yading@10:                 dst += len;
yading@10:             } else {
yading@10:                 dst -= len;
yading@10:                 memset(dst, val, len);
yading@10:             }
yading@10:             break;
yading@10:         }
yading@10:         if (dst == dst_end)
yading@10:             return 0;
yading@10:     }
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
yading@10:                         AVPacket *pkt)
yading@10: {
yading@10:     BMVDecContext * const c = avctx->priv_data;
yading@10:     AVFrame *frame = data;
yading@10:     int type, scr_off;
yading@10:     int i, ret;
yading@10:     uint8_t *srcptr, *outptr;
yading@10: 
yading@10:     c->stream = pkt->data;
yading@10:     type = bytestream_get_byte(&c->stream);
yading@10:     if (type & BMV_AUDIO) {
yading@10:         int blobs = bytestream_get_byte(&c->stream);
yading@10:         if (pkt->size < blobs * 65 + 2) {
yading@10:             av_log(avctx, AV_LOG_ERROR, "Audio data doesn't fit in frame\n");
yading@10:             return AVERROR_INVALIDDATA;
yading@10:         }
yading@10:         c->stream += blobs * 65;
yading@10:     }
yading@10:     if (type & BMV_COMMAND) {
yading@10:         int command_size = (type & BMV_PRINT) ? 8 : 10;
yading@10:         if (c->stream - pkt->data + command_size > pkt->size) {
yading@10:             av_log(avctx, AV_LOG_ERROR, "Command data doesn't fit in frame\n");
yading@10:             return AVERROR_INVALIDDATA;
yading@10:         }
yading@10:         c->stream += command_size;
yading@10:     }
yading@10:     if (type & BMV_PALETTE) {
yading@10:         if (c->stream - pkt->data > pkt->size - 768) {
yading@10:             av_log(avctx, AV_LOG_ERROR, "Palette data doesn't fit in frame\n");
yading@10:             return AVERROR_INVALIDDATA;
yading@10:         }
yading@10:         for (i = 0; i < 256; i++)
yading@10:             c->pal[i] = 0xFFU << 24 | bytestream_get_be24(&c->stream);
yading@10:     }
yading@10:     if (type & BMV_SCROLL) {
yading@10:         if (c->stream - pkt->data > pkt->size - 2) {
yading@10:             av_log(avctx, AV_LOG_ERROR, "Screen offset data doesn't fit in frame\n");
yading@10:             return AVERROR_INVALIDDATA;
yading@10:         }
yading@10:         scr_off = (int16_t)bytestream_get_le16(&c->stream);
yading@10:     } else if ((type & BMV_INTRA) == BMV_INTRA) {
yading@10:         scr_off = -640;
yading@10:     } else {
yading@10:         scr_off = 0;
yading@10:     }
yading@10: 
yading@10:     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
yading@10:         return ret;
yading@10: 
yading@10:     if (decode_bmv_frame(c->stream, pkt->size - (c->stream - pkt->data), c->frame, scr_off)) {
yading@10:         av_log(avctx, AV_LOG_ERROR, "Error decoding frame data\n");
yading@10:         return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     memcpy(frame->data[1], c->pal, AVPALETTE_SIZE);
yading@10:     frame->palette_has_changed = type & BMV_PALETTE;
yading@10: 
yading@10:     outptr = frame->data[0];
yading@10:     srcptr = c->frame;
yading@10: 
yading@10:     for (i = 0; i < avctx->height; i++) {
yading@10:         memcpy(outptr, srcptr, avctx->width);
yading@10:         srcptr += avctx->width;
yading@10:         outptr += frame->linesize[0];
yading@10:     }
yading@10: 
yading@10:     *got_frame = 1;
yading@10: 
yading@10:     /* always report that the buffer was completely consumed */
yading@10:     return pkt->size;
yading@10: }
yading@10: 
yading@10: static av_cold int decode_init(AVCodecContext *avctx)
yading@10: {
yading@10:     BMVDecContext * const c = avctx->priv_data;
yading@10: 
yading@10:     c->avctx = avctx;
yading@10:     avctx->pix_fmt = AV_PIX_FMT_PAL8;
yading@10: 
yading@10:     if (avctx->width != SCREEN_WIDE || avctx->height != SCREEN_HIGH) {
yading@10:         av_log(avctx, AV_LOG_ERROR, "Invalid dimension %dx%d\n", avctx->width, avctx->height);
yading@10:         return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     c->frame = c->frame_base + 640;
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static const int bmv_aud_mults[16] = {
yading@10:     16512, 8256, 4128, 2064, 1032, 516, 258, 192, 129, 88, 64, 56, 48, 40, 36, 32
yading@10: };
yading@10: 
yading@10: static av_cold int bmv_aud_decode_init(AVCodecContext *avctx)
yading@10: {
yading@10:     avctx->channels       = 2;
yading@10:     avctx->channel_layout = AV_CH_LAYOUT_STEREO;
yading@10:     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int bmv_aud_decode_frame(AVCodecContext *avctx, void *data,
yading@10:                                 int *got_frame_ptr, AVPacket *avpkt)
yading@10: {
yading@10:     AVFrame *frame     = data;
yading@10:     const uint8_t *buf = avpkt->data;
yading@10:     int buf_size = avpkt->size;
yading@10:     int blocks = 0, total_blocks, i;
yading@10:     int ret;
yading@10:     int16_t *output_samples;
yading@10:     int scale[2];
yading@10: 
yading@10:     total_blocks = *buf++;
yading@10:     if (buf_size < total_blocks * 65 + 1) {
yading@10:         av_log(avctx, AV_LOG_ERROR, "expected %d bytes, got %d\n",
yading@10:                total_blocks * 65 + 1, buf_size);
yading@10:         return AVERROR_INVALIDDATA;
yading@10:     }
yading@10: 
yading@10:     /* get output buffer */
yading@10:     frame->nb_samples = total_blocks * 32;
yading@10:     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
yading@10:         return ret;
yading@10:     output_samples = (int16_t *)frame->data[0];
yading@10: 
yading@10:     for (blocks = 0; blocks < total_blocks; blocks++) {
yading@10:         uint8_t code = *buf++;
yading@10:         code = (code >> 1) | (code << 7);
yading@10:         scale[0] = bmv_aud_mults[code & 0xF];
yading@10:         scale[1] = bmv_aud_mults[code >> 4];
yading@10:         for (i = 0; i < 32; i++) {
yading@10:             *output_samples++ = av_clip_int16((scale[0] * (int8_t)*buf++) >> 5);
yading@10:             *output_samples++ = av_clip_int16((scale[1] * (int8_t)*buf++) >> 5);
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     *got_frame_ptr = 1;
yading@10: 
yading@10:     return buf_size;
yading@10: }
yading@10: 
yading@10: AVCodec ff_bmv_video_decoder = {
yading@10:     .name           = "bmv_video",
yading@10:     .type           = AVMEDIA_TYPE_VIDEO,
yading@10:     .id             = AV_CODEC_ID_BMV_VIDEO,
yading@10:     .priv_data_size = sizeof(BMVDecContext),
yading@10:     .init           = decode_init,
yading@10:     .decode         = decode_frame,
yading@10:     .capabilities   = CODEC_CAP_DR1,
yading@10:     .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV video"),
yading@10: };
yading@10: 
yading@10: AVCodec ff_bmv_audio_decoder = {
yading@10:     .name           = "bmv_audio",
yading@10:     .type           = AVMEDIA_TYPE_AUDIO,
yading@10:     .id             = AV_CODEC_ID_BMV_AUDIO,
yading@10:     .init           = bmv_aud_decode_init,
yading@10:     .decode         = bmv_aud_decode_frame,
yading@10:     .capabilities   = CODEC_CAP_DR1,
yading@10:     .long_name      = NULL_IF_CONFIG_SMALL("Discworld II BMV audio"),
yading@10: };