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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 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 
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 "sauce.h"
00035 
00036 typedef struct {
00037     AVClass *class;
00038     int chars_per_frame;
00039     uint64_t fsize;  
00040     char *video_size;
00041     char *framerate; 
00042 } TtyDemuxContext;
00043 
00047 static int efi_read(AVFormatContext *avctx, uint64_t start_pos)
00048 {
00049     TtyDemuxContext *s = avctx->priv_data;
00050     AVIOContext *pb = avctx->pb;
00051     char buf[37];
00052     int len;
00053 
00054     avio_seek(pb, start_pos, SEEK_SET);
00055     if (avio_r8(pb) != 0x1A)
00056         return -1;
00057 
00058 #define GET_EFI_META(name,size) \
00059     len = avio_r8(pb); \
00060     if (len < 1 || len > size) \
00061         return -1; \
00062     if (avio_read(pb, buf, size) == size) { \
00063         buf[len] = 0; \
00064         av_dict_set(&avctx->metadata, name, buf, 0); \
00065     }
00066 
00067     GET_EFI_META("filename", 12)
00068     GET_EFI_META("title",    36)
00069 
00070     s->fsize = start_pos;
00071     return 0;
00072 }
00073 
00074 static int read_header(AVFormatContext *avctx,
00075                        AVFormatParameters *ap)
00076 {
00077     TtyDemuxContext *s = avctx->priv_data;
00078     int width = 0, height = 0, ret = 0;
00079     AVStream *st = av_new_stream(avctx, 0);
00080     AVRational framerate;
00081 
00082     if (!st) {
00083         ret = AVERROR(ENOMEM);
00084         goto fail;
00085     }
00086     st->codec->codec_tag   = 0;
00087     st->codec->codec_type  = AVMEDIA_TYPE_VIDEO;
00088     st->codec->codec_id    = CODEC_ID_ANSI;
00089 
00090     if (s->video_size && (ret = av_parse_video_size(&width, &height, s->video_size)) < 0) {
00091         av_log (avctx, AV_LOG_ERROR, "Couldn't parse video size.\n");
00092         goto fail;
00093     }
00094     if ((ret = av_parse_video_rate(&framerate, s->framerate)) < 0) {
00095         av_log(avctx, AV_LOG_ERROR, "Could not parse framerate: %s.\n", s->framerate);
00096         goto fail;
00097     }
00098 #if FF_API_FORMAT_PARAMETERS
00099     if (ap->width > 0)
00100         width = ap->width;
00101     if (ap->height > 0)
00102         height = ap->height;
00103     if (ap->time_base.num)
00104         framerate = (AVRational){ap->time_base.den, ap->time_base.num};
00105 #endif
00106     st->codec->width  = width;
00107     st->codec->height = height;
00108     av_set_pts_info(st, 60, framerate.den, framerate.num);
00109 
00110     /* simulate tty display speed */
00111 #if FF_API_FORMAT_PARAMETERS
00112     if (ap->sample_rate)
00113         s->chars_per_frame = ap->sample_rate;
00114 #endif
00115     s->chars_per_frame = FFMAX(av_q2d(st->time_base)*s->chars_per_frame, 1);
00116 
00117     if (avctx->pb->seekable) {
00118         s->fsize = avio_size(avctx->pb);
00119         st->duration = (s->fsize + s->chars_per_frame - 1) / s->chars_per_frame;
00120 
00121         if (ff_sauce_read(avctx, &s->fsize, 0, 0) < 0)
00122             efi_read(avctx, s->fsize - 51);
00123 
00124         avio_seek(avctx->pb, 0, SEEK_SET);
00125     }
00126 
00127 fail:
00128     return ret;
00129 }
00130 
00131 static int read_packet(AVFormatContext *avctx, AVPacket *pkt)
00132 {
00133     TtyDemuxContext *s = avctx->priv_data;
00134     int n;
00135 
00136     if (url_feof(avctx->pb))
00137         return AVERROR_EOF;
00138 
00139     n = s->chars_per_frame;
00140     if (s->fsize) {
00141         // ignore metadata buffer
00142         uint64_t p = avio_tell(avctx->pb);
00143         if (p + s->chars_per_frame > s->fsize)
00144             n = s->fsize - p;
00145     }
00146 
00147     pkt->size = av_get_packet(avctx->pb, pkt, n);
00148     if (pkt->size <= 0)
00149         return AVERROR(EIO);
00150     pkt->flags |= AV_PKT_FLAG_KEY;
00151     return 0;
00152 }
00153 
00154 #define OFFSET(x) offsetof(TtyDemuxContext, x)
00155 #define DEC AV_OPT_FLAG_DECODING_PARAM
00156 static const AVOption options[] = {
00157     { "chars_per_frame", "", offsetof(TtyDemuxContext, chars_per_frame), FF_OPT_TYPE_INT, {.dbl = 6000}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM},
00158     { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), FF_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
00159     { "framerate", "", OFFSET(framerate), FF_OPT_TYPE_STRING, {.str = "25"}, 0, 0, DEC },
00160     { NULL },
00161 };
00162 
00163 static const AVClass tty_demuxer_class = {
00164     .class_name     = "TTY demuxer",
00165     .item_name      = av_default_item_name,
00166     .option         = options,
00167     .version        = LIBAVUTIL_VERSION_INT,
00168 };
00169 
00170 AVInputFormat ff_tty_demuxer = {
00171     .name           = "tty",
00172     .long_name      = NULL_IF_CONFIG_SMALL("Tele-typewriter"),
00173     .priv_data_size = sizeof(TtyDemuxContext),
00174     .read_header    = read_header,
00175     .read_packet    = read_packet,
00176     .extensions     = "ans,art,asc,diz,ice,nfo,txt,vt",
00177     .priv_class     = &tty_demuxer_class,
00178 };

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