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libavformat/tty.c

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00001 /*
00002  * Tele-typewriter demuxer
00003  * Copyright (c) 2010 Peter Ross <pross@xvid.org>
00004  *
00005  * This file is part of Libav.
00006  *
00007  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include "libavutil/intreadwrite.h"
00028 #include "libavutil/avstring.h"
00029 #include "libavutil/log.h"
00030 #include "libavutil/dict.h"
00031 #include "libavutil/opt.h"
00032 #include "libavutil/parseutils.h"
00033 #include "avformat.h"
00034 #include "internal.h"
00035 #include "sauce.h"
00036 
00037 typedef struct {
00038     AVClass *class;
00039     int chars_per_frame;
00040     uint64_t fsize;  
00041     char *video_size;
00042     char *framerate; 
00043 } TtyDemuxContext;
00044 
00048 static int efi_read(AVFormatContext *avctx, uint64_t start_pos)
00049 {
00050     TtyDemuxContext *s = avctx->priv_data;
00051     AVIOContext *pb = avctx->pb;
00052     char buf[37];
00053     int len;
00054 
00055     avio_seek(pb, start_pos, SEEK_SET);
00056     if (avio_r8(pb) != 0x1A)
00057         return -1;
00058 
00059 #define GET_EFI_META(name,size) \
00060     len = avio_r8(pb); \
00061     if (len < 1 || len > size) \
00062         return -1; \
00063     if (avio_read(pb, buf, size) == size) { \
00064         buf[len] = 0; \
00065         av_dict_set(&avctx->metadata, name, buf, 0); \
00066     }
00067 
00068     GET_EFI_META("filename", 12)
00069     GET_EFI_META("title",    36)
00070 
00071     s->fsize = start_pos;
00072     return 0;
00073 }
00074 
00075 static int read_header(AVFormatContext *avctx,
00076                        AVFormatParameters *ap)
00077 {
00078     TtyDemuxContext *s = avctx->priv_data;
00079     int width = 0, height = 0, ret = 0;
00080     AVStream *st = avformat_new_stream(avctx, NULL);
00081     AVRational framerate;
00082 
00083     if (!st) {
00084         ret = AVERROR(ENOMEM);
00085         goto fail;
00086     }
00087     st->codec->codec_tag   = 0;
00088     st->codec->codec_type  = AVMEDIA_TYPE_VIDEO;
00089     st->codec->codec_id    = CODEC_ID_ANSI;
00090 
00091     if (s->video_size && (ret = av_parse_video_size(&width, &height, s->video_size)) < 0) {
00092         av_log (avctx, AV_LOG_ERROR, "Couldn't parse video size.\n");
00093         goto fail;
00094     }
00095     if ((ret = av_parse_video_rate(&framerate, s->framerate)) < 0) {
00096         av_log(avctx, AV_LOG_ERROR, "Could not parse framerate: %s.\n", s->framerate);
00097         goto fail;
00098     }
00099     st->codec->width  = width;
00100     st->codec->height = height;
00101     avpriv_set_pts_info(st, 60, framerate.den, framerate.num);
00102 
00103     /* simulate tty display speed */
00104     s->chars_per_frame = FFMAX(av_q2d(st->time_base)*s->chars_per_frame, 1);
00105 
00106     if (avctx->pb->seekable) {
00107         s->fsize = avio_size(avctx->pb);
00108         st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;
00109 
00110         if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)
00111             efi_read(avctx, s->fsize - 51);
00112 
00113         avio_seek(avctx->pb, 0, SEEK_SET);
00114     }
00115 
00116 fail:
00117     return ret;
00118 }
00119 
00120 static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
00121 {
00122     TtyDemuxContext *s = avctx->priv_data;
00123     int n;
00124 
00125     if (avctx->pb->eof_reached)
00126         return AVERROR_EOF;
00127 
00128     n = s->chars_per_frame;
00129     if (s->fsize) {
00130         // ignore metadata buffer
00131         uint64_t p = avio_tell(avctx->pb);
00132         if (p + s->chars_per_frame > s->fsize)
00133             n = s->fsize - p;
00134     }
00135 
00136     pkt->size = av_get_packet(avctx->pb, pkt, n);
00137     if (pkt->size <= 0)
00138         return AVERROR(EIO);
00139     pkt->flags |= AV_PKT_FLAG_KEY;
00140     return 0;
00141 }
00142 
00143 #define OFFSET(x) offsetof(TtyDemuxContext, x)
00144 #define DEC AV_OPT_FLAG_DECODING_PARAM
00145 static const AVOption options[] = {
00146     { "chars_per_frame", "", offsetof(TtyDemuxContext, chars_per_frame), AV_OPT_TYPE_INT, {.dbl = 6000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM},
00147     { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
00148     { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "25"}, 0, 0, DEC },
00149     { NULL },
00150 };
00151 
00152 static const AVClass tty_demuxer_class = {
00153     .class_name     = "TTY demuxer",
00154     .item_name      = av_default_item_name,
00155     .option         = options,
00156     .version        = LIBAVUTIL_VERSION_INT,
00157 };
00158 
00159 AVInputFormat ff_tty_demuxer = {
00160     .name           = "tty",
00161     .long_name      = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
00162     .priv_data_size = sizeof(TtyDemuxContext),
00163     .read_header    = read_header,
00164     .read_packet    = read_packet,
00165     .extensions     = "ans,art,asc,diz,ice,nfo,txt,vt",
00166     .priv_class     = &tty_demuxer_class,
00167 };
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