FFmpeg: libavformat/bethsoftvid.c Source File

00001 /*
00002  * Bethsoft VID format Demuxer
00003  * Copyright (c) 2007 Nicholas Tung
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00030 #include "libavutil/intreadwrite.h"
00031 #include "avformat.h"
00032 #include "internal.h"
00033 #include "libavcodec/bethsoftvideo.h"
00034 
00035 typedef struct BVID_DemuxContext
00036 {
00037     int nframes;
00041     int bethsoft_global_delay;
00042 
00045     int video_pts;
00046 
00047     int is_finished;
00048 
00049 } BVID_DemuxContext;
00050 
00051 static int vid_probe(AVProbeData *p)
00052 {
00053     // little endian VID tag, file starts with "VID\0"
00054     if (AV_RL32(p->buf) != MKTAG('V', 'I', 'D', 0))
00055         return 0;
00056 
00057     return AVPROBE_SCORE_MAX;
00058 }
00059 
00060 static int vid_read_header(AVFormatContext *s,
00061                             AVFormatParameters *ap)
00062 {
00063     BVID_DemuxContext *vid = s->priv_data;
00064     AVIOContext *pb = s->pb;
00065     AVStream *stream;
00066 
00067     /* load main header. Contents:
00068     *    bytes: 'V' 'I' 'D'
00069     *    int16s: always_512, nframes, width, height, delay, always_14
00070     */
00071     avio_skip(pb, 5);
00072     vid->nframes = avio_rl16(pb);
00073 
00074     stream = avformat_new_stream(s, NULL);
00075     if (!stream)
00076         return AVERROR(ENOMEM);
00077     avpriv_set_pts_info(stream, 32, 1, 60);     // 16 ms increments, i.e. 60 fps
00078     stream->codec->codec_type = AVMEDIA_TYPE_VIDEO;
00079     stream->codec->codec_id = CODEC_ID_BETHSOFTVID;
00080     stream->codec->width = avio_rl16(pb);
00081     stream->codec->height = avio_rl16(pb);
00082     stream->codec->pix_fmt = PIX_FMT_PAL8;
00083     vid->bethsoft_global_delay = avio_rl16(pb);
00084     avio_rl16(pb);
00085 
00086     // done with video codec, set up audio codec
00087     stream = avformat_new_stream(s, NULL);
00088     if (!stream)
00089         return AVERROR(ENOMEM);
00090     stream->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00091     stream->codec->codec_id = CODEC_ID_PCM_U8;
00092     stream->codec->channels = 1;
00093     stream->codec->sample_rate = 11025;
00094     stream->codec->bits_per_coded_sample = 8;
00095     stream->codec->bit_rate = stream->codec->channels * stream->codec->sample_rate * stream->codec->bits_per_coded_sample;
00096 
00097     return 0;
00098 }
00099 
00100 #define BUFFER_PADDING_SIZE 1000
00101 static int read_frame(BVID_DemuxContext *vid, AVIOContext *pb, AVPacket *pkt,
00102                       uint8_t block_type, AVFormatContext *s, int npixels)
00103 {
00104     uint8_t * vidbuf_start = NULL;
00105     int vidbuf_nbytes = 0;
00106     int code;
00107     int bytes_copied = 0;
00108     int position;
00109     unsigned int vidbuf_capacity;
00110 
00111     vidbuf_start = av_malloc(vidbuf_capacity = BUFFER_PADDING_SIZE);
00112     if(!vidbuf_start)
00113         return AVERROR(ENOMEM);
00114 
00115     // save the file position for the packet, include block type
00116     position = avio_tell(pb) - 1;
00117 
00118     vidbuf_start[vidbuf_nbytes++] = block_type;
00119 
00120     // get the video delay (next int16), and set the presentation time
00121     vid->video_pts += vid->bethsoft_global_delay + avio_rl16(pb);
00122 
00123     // set the y offset if it exists (decoder header data should be in data section)
00124     if(block_type == VIDEO_YOFF_P_FRAME){
00125         if(avio_read(pb, &vidbuf_start[vidbuf_nbytes], 2) != 2)
00126             goto fail;
00127         vidbuf_nbytes += 2;
00128     }
00129 
00130     do{
00131         vidbuf_start = av_fast_realloc(vidbuf_start, &vidbuf_capacity, vidbuf_nbytes + BUFFER_PADDING_SIZE);
00132         if(!vidbuf_start)
00133             return AVERROR(ENOMEM);
00134 
00135         code = avio_r8(pb);
00136         vidbuf_start[vidbuf_nbytes++] = code;
00137 
00138         if(code >= 0x80){ // rle sequence
00139             if(block_type == VIDEO_I_FRAME)
00140                 vidbuf_start[vidbuf_nbytes++] = avio_r8(pb);
00141         } else if(code){ // plain sequence
00142             if(avio_read(pb, &vidbuf_start[vidbuf_nbytes], code) != code)
00143                 goto fail;
00144             vidbuf_nbytes += code;
00145         }
00146         bytes_copied += code & 0x7F;
00147         if(bytes_copied == npixels){ // sometimes no stop character is given, need to keep track of bytes copied
00148             // may contain a 0 byte even if read all pixels
00149             if(avio_r8(pb))
00150                 avio_seek(pb, -1, SEEK_CUR);
00151             break;
00152         }
00153         if(bytes_copied > npixels)
00154             goto fail;
00155     } while(code);
00156 
00157     // copy data into packet
00158     if(av_new_packet(pkt, vidbuf_nbytes) < 0)
00159         goto fail;
00160     memcpy(pkt->data, vidbuf_start, vidbuf_nbytes);
00161     av_free(vidbuf_start);
00162 
00163     pkt->pos = position;
00164     pkt->stream_index = 0;  // use the video decoder, which was initialized as the first stream
00165     pkt->pts = vid->video_pts;
00166 
00167     vid->nframes--;  // used to check if all the frames were read
00168     return vidbuf_nbytes;
00169 fail:
00170     av_free(vidbuf_start);
00171     return -1;
00172 }
00173 
00174 static int vid_read_packet(AVFormatContext *s,
00175                            AVPacket *pkt)
00176 {
00177     BVID_DemuxContext *vid = s->priv_data;
00178     AVIOContext *pb = s->pb;
00179     unsigned char block_type;
00180     int audio_length;
00181     int ret_value;
00182 
00183     if(vid->is_finished || url_feof(pb))
00184         return AVERROR(EIO);
00185 
00186     block_type = avio_r8(pb);
00187     switch(block_type){
00188         case PALETTE_BLOCK:
00189             avio_seek(pb, -1, SEEK_CUR);     // include block type
00190             ret_value = av_get_packet(pb, pkt, 3 * 256 + 1);
00191             if(ret_value != 3 * 256 + 1){
00192                 av_free_packet(pkt);
00193                 return AVERROR(EIO);
00194             }
00195             pkt->stream_index = 0;
00196             return ret_value;
00197 
00198         case FIRST_AUDIO_BLOCK:
00199             avio_rl16(pb);
00200             // soundblaster DAC used for sample rate, as on specification page (link above)
00201             s->streams[1]->codec->sample_rate = 1000000 / (256 - avio_r8(pb));
00202             s->streams[1]->codec->bit_rate = s->streams[1]->codec->channels * s->streams[1]->codec->sample_rate * s->streams[1]->codec->bits_per_coded_sample;
00203         case AUDIO_BLOCK:
00204             audio_length = avio_rl16(pb);
00205             ret_value = av_get_packet(pb, pkt, audio_length);
00206             pkt->stream_index = 1;
00207             return ret_value != audio_length ? AVERROR(EIO) : ret_value;
00208 
00209         case VIDEO_P_FRAME:
00210         case VIDEO_YOFF_P_FRAME:
00211         case VIDEO_I_FRAME:
00212             return read_frame(vid, pb, pkt, block_type, s,
00213                               s->streams[0]->codec->width * s->streams[0]->codec->height);
00214 
00215         case EOF_BLOCK:
00216             if(vid->nframes != 0)
00217                 av_log(s, AV_LOG_VERBOSE, "reached terminating character but not all frames read.\n");
00218             vid->is_finished = 1;
00219             return AVERROR(EIO);
00220         default:
00221             av_log(s, AV_LOG_ERROR, "unknown block (character = %c, decimal = %d, hex = %x)!!!\n",
00222                    block_type, block_type, block_type); return -1;
00223     }
00224 }
00225 
00226 AVInputFormat ff_bethsoftvid_demuxer = {
00227     .name           = "bethsoftvid",
00228     .long_name      = NULL_IF_CONFIG_SMALL("Bethesda Softworks VID format"),
00229     .priv_data_size = sizeof(BVID_DemuxContext),
00230     .read_probe     = vid_probe,
00231     .read_header    = vid_read_header,
00232     .read_packet    = vid_read_packet,
00233 };