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libavformat/bfi.c

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00001 /*
00002  * Brute Force & Ignorance (BFI) demuxer
00003  * Copyright (c) 2008 Sisir Koppaka
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 
00029 #include "libavutil/intreadwrite.h"
00030 #include "avformat.h"
00031 
00032 typedef struct BFIContext {
00033     int nframes;
00034     int audio_frame;
00035     int video_frame;
00036     int video_size;
00037     int avflag;
00038 } BFIContext;
00039 
00040 static int bfi_probe(AVProbeData * p)
00041 {
00042     /* Check file header */
00043     if (AV_RL32(p->buf) == MKTAG('B', 'F', '&', 'I'))
00044         return AVPROBE_SCORE_MAX;
00045     else
00046         return 0;
00047 }
00048 
00049 static int bfi_read_header(AVFormatContext * s, AVFormatParameters * ap)
00050 {
00051     BFIContext *bfi = s->priv_data;
00052     ByteIOContext *pb = s->pb;
00053     AVStream *vstream;
00054     AVStream *astream;
00055     int fps, chunk_header;
00056 
00057     /* Initialize the video codec... */
00058     vstream = av_new_stream(s, 0);
00059     if (!vstream)
00060         return AVERROR(ENOMEM);
00061 
00062     /* Initialize the audio codec... */
00063     astream = av_new_stream(s, 0);
00064     if (!astream)
00065         return AVERROR(ENOMEM);
00066 
00067     /* Set the total number of frames. */
00068     url_fskip(pb, 8);
00069     chunk_header           = get_le32(pb);
00070     bfi->nframes           = get_le32(pb);
00071     get_le32(pb);
00072     get_le32(pb);
00073     get_le32(pb);
00074     fps                    = get_le32(pb);
00075     url_fskip(pb, 12);
00076     vstream->codec->width  = get_le32(pb);
00077     vstream->codec->height = get_le32(pb);
00078 
00079     /*Load the palette to extradata */
00080     url_fskip(pb, 8);
00081     vstream->codec->extradata      = av_malloc(768);
00082     vstream->codec->extradata_size = 768;
00083     get_buffer(pb, vstream->codec->extradata,
00084                vstream->codec->extradata_size);
00085 
00086     astream->codec->sample_rate = get_le32(pb);
00087 
00088     /* Set up the video codec... */
00089     av_set_pts_info(vstream, 32, 1, fps);
00090     vstream->codec->codec_type = AVMEDIA_TYPE_VIDEO;
00091     vstream->codec->codec_id   = CODEC_ID_BFI;
00092     vstream->codec->pix_fmt    = PIX_FMT_PAL8;
00093 
00094     /* Set up the audio codec now... */
00095     astream->codec->codec_type      = AVMEDIA_TYPE_AUDIO;
00096     astream->codec->codec_id        = CODEC_ID_PCM_U8;
00097     astream->codec->channels        = 1;
00098     astream->codec->bits_per_coded_sample = 8;
00099     astream->codec->bit_rate        =
00100         astream->codec->sample_rate * astream->codec->bits_per_coded_sample;
00101     url_fseek(pb, chunk_header - 3, SEEK_SET);
00102     av_set_pts_info(astream, 64, 1, astream->codec->sample_rate);
00103     return 0;
00104 }
00105 
00106 
00107 static int bfi_read_packet(AVFormatContext * s, AVPacket * pkt)
00108 {
00109     BFIContext *bfi = s->priv_data;
00110     ByteIOContext *pb = s->pb;
00111     int ret, audio_offset, video_offset, chunk_size, audio_size = 0;
00112     if (bfi->nframes == 0 || url_feof(pb)) {
00113         return AVERROR(EIO);
00114     }
00115 
00116     /* If all previous chunks were completely read, then find a new one... */
00117     if (!bfi->avflag) {
00118         uint32_t state = 0;
00119         while(state != MKTAG('S','A','V','I')){
00120             if (url_feof(pb))
00121                 return AVERROR(EIO);
00122             state = 256*state + get_byte(pb);
00123         }
00124         /* Now that the chunk's location is confirmed, we proceed... */
00125         chunk_size      = get_le32(pb);
00126         get_le32(pb);
00127         audio_offset    = get_le32(pb);
00128         get_le32(pb);
00129         video_offset    = get_le32(pb);
00130         audio_size      = video_offset - audio_offset;
00131         bfi->video_size = chunk_size - video_offset;
00132 
00133         //Tossing an audio packet at the audio decoder.
00134         ret = av_get_packet(pb, pkt, audio_size);
00135         if (ret < 0)
00136             return ret;
00137 
00138         pkt->pts          = bfi->audio_frame;
00139         bfi->audio_frame += ret;
00140     }
00141 
00142     else {
00143 
00144         //Tossing a video packet at the video decoder.
00145         ret = av_get_packet(pb, pkt, bfi->video_size);
00146         if (ret < 0)
00147             return ret;
00148 
00149         pkt->pts          = bfi->video_frame;
00150         bfi->video_frame += ret / bfi->video_size;
00151 
00152         /* One less frame to read. A cursory decrement. */
00153         bfi->nframes--;
00154     }
00155 
00156     bfi->avflag       = !bfi->avflag;
00157     pkt->stream_index = bfi->avflag;
00158     return ret;
00159 }
00160 
00161 AVInputFormat bfi_demuxer = {
00162     "bfi",
00163     NULL_IF_CONFIG_SMALL("Brute Force & Ignorance"),
00164     sizeof(BFIContext),
00165     bfi_probe,
00166     bfi_read_header,
00167     bfi_read_packet,
00168 };

Generated on Fri Sep 16 2011 17:17:34 for FFmpeg by  doxygen 1.7.1