FFmpeg: libavformat/mtv.c Source File

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libavformat

mtv.c

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1 /*

2 * mtv demuxer

4 *

5 * This file is part of FFmpeg.

6 *

7 * FFmpeg is free software; you can redistribute it and/or

8 * modify it under the terms of the GNU Lesser General Public

9 * License as published by the Free Software Foundation; either

10 * version 2.1 of the License, or (at your option) any later version.

11 *

12 * FFmpeg is distributed in the hope that it will be useful,

13 * but WITHOUT ANY WARRANTY; without even the implied warranty of

14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

15 * Lesser General Public License for more details.

16 *

17 * You should have received a copy of the GNU Lesser General Public

18 * License along with FFmpeg; if not, write to the Free Software

19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

20 */

22 /**

23 * @file

24 * MTV demuxer.

25 */

27 #include "libavutil/bswap.h"

28 #include "libavutil/intreadwrite.h"

29 #include "avformat.h"

30 #include "internal.h"

32 #define MTV_ASUBCHUNK_DATA_SIZE 500

33 #define MTV_HEADER_SIZE 512

34 #define MTV_AUDIO_PADDING_SIZE 12

35 #define AUDIO_SAMPLING_RATE 44100

37 typedef struct MTVDemuxContext {

39 unsigned int file_size; ///< filesize, not always right

40 unsigned int segments; ///< number of 512 byte segments

41 unsigned int audio_identifier; ///< 'MP3' on all files I have seen

42 unsigned int audio_br; ///< bitrate of audio channel (mp3)

43 unsigned int img_colorfmt; ///< frame colorfmt rgb 565/555

44 unsigned int img_bpp; ///< frame bits per pixel

45 unsigned int img_width;

46 unsigned int img_height;

47 unsigned int img_segment_size; ///< size of image segment

48 unsigned int video_fps;

49 unsigned int full_segment_size;

51 } MTVDemuxContext;

53 static int mtv_probe(AVProbeData *p)

54 {

55 /* Magic is 'AMV' */

56 if (*p->buf != 'A' || *(p->buf + 1) != 'M' || *(p->buf + 2) != 'V')

57 return 0;

59 /* Check for nonzero in bpp and (width|height) header fields */

60 if(p->buf_size < 57 || !(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))

61 return 0;

63 /* If width or height are 0 then imagesize header field should not */

64 if(!AV_RL16(&p->buf[52]) || !AV_RL16(&p->buf[54]))

65 {

66 if(!!AV_RL16(&p->buf[56]))

67 return AVPROBE_SCORE_EXTENSION;

68 else

69 return 0;

70 }

72 if(p->buf[51] != 16)

73 return AVPROBE_SCORE_EXTENSION / 2; // But we are going to assume 16bpp anyway ..

75 return AVPROBE_SCORE_MAX;

76 }

78 static int mtv_read_header(AVFormatContext *s)

79 {

80 MTVDemuxContext *mtv = s->priv_data;

81 AVIOContext *pb = s->pb;

82 AVStream *st;

83 unsigned int audio_subsegments;

85 avio_skip(pb, 3);

86 mtv->file_size = avio_rl32(pb);

87 mtv->segments = avio_rl32(pb);

88 avio_skip(pb, 32);

89 mtv->audio_identifier = avio_rl24(pb);

90 mtv->audio_br = avio_rl16(pb);

91 mtv->img_colorfmt = avio_rl24(pb);

92 mtv->img_bpp = avio_r8(pb);

93 mtv->img_width = avio_rl16(pb);

94 mtv->img_height = avio_rl16(pb);

95 mtv->img_segment_size = avio_rl16(pb);

97 /* Calculate width and height if missing from header */

99 if(mtv->img_bpp>>3){

100 if(!mtv->img_width && mtv->img_height)

101 mtv->img_width=mtv->img_segment_size / (mtv->img_bpp>>3)

102 / mtv->img_height;

103

104 if(!mtv->img_height && mtv->img_width)

105 mtv->img_height=mtv->img_segment_size / (mtv->img_bpp>>3)

106 / mtv->img_width;

107 }

108 if(!mtv->img_height || !mtv->img_width || !mtv->img_segment_size){

109 av_log(s, AV_LOG_ERROR, "width or height or segment_size is invalid and I cannot calculate them from other information\n");

110 return AVERROR(EINVAL);

111 }

112

113 avio_skip(pb, 4);

114 audio_subsegments = avio_rl16(pb);

115

116 if (audio_subsegments == 0) {

117 avpriv_request_sample(s, "MTV files without audio");

118 return AVERROR_PATCHWELCOME;

119 }

120

121 mtv->full_segment_size =

122 audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +

123 mtv->img_segment_size;

124 mtv->video_fps = (mtv->audio_br / 4) / audio_subsegments;

125

126 // FIXME Add sanity check here

127

128 // all systems go! init decoders

129

130 // video - raw rgb565

131

132 st = avformat_new_stream(s, NULL);

133 if(!st)

134 return AVERROR(ENOMEM);

135

136 avpriv_set_pts_info(st, 64, 1, mtv->video_fps);

137 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

138 st->codec->codec_id = AV_CODEC_ID_RAWVIDEO;

139 st->codec->pix_fmt = AV_PIX_FMT_RGB565BE;

140 st->codec->width = mtv->img_width;

141 st->codec->height = mtv->img_height;

142 st->codec->sample_rate = mtv->video_fps;

143 st->codec->extradata = av_strdup("BottomUp");

144 st->codec->extradata_size = 9;

145

146 // audio - mp3

147

148 st = avformat_new_stream(s, NULL);

149 if(!st)

150 return AVERROR(ENOMEM);

151

152 avpriv_set_pts_info(st, 64, 1, AUDIO_SAMPLING_RATE);

153 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

154 st->codec->codec_id = AV_CODEC_ID_MP3;

155 st->codec->bit_rate = mtv->audio_br;

156 st->need_parsing = AVSTREAM_PARSE_FULL;

157

158 // Jump over header

159

160 if(avio_seek(pb, MTV_HEADER_SIZE, SEEK_SET) != MTV_HEADER_SIZE)

161 return AVERROR(EIO);

162

163 return 0;

164

165 }

166

167 static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)

168 {

169 MTVDemuxContext *mtv = s->priv_data;

170 AVIOContext *pb = s->pb;

171 int ret;

172

173 if((avio_tell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)

174 {

175 avio_skip(pb, MTV_AUDIO_PADDING_SIZE);

176

177 ret = av_get_packet(pb, pkt, MTV_ASUBCHUNK_DATA_SIZE);

178 if(ret < 0)

179 return ret;

180

181 pkt->pos -= MTV_AUDIO_PADDING_SIZE;

182 pkt->stream_index = 1;

183

184 }else

185 {

186 ret = av_get_packet(pb, pkt, mtv->img_segment_size);

187 if(ret < 0)

188 return ret;

189

190 pkt->stream_index = 0;

191 }

192

193 return ret;

194 }

195

196 AVInputFormat ff_mtv_demuxer = {

197 .name = "mtv",

198 .long_name = NULL_IF_CONFIG_SMALL("MTV"),

199 .priv_data_size = sizeof(MTVDemuxContext),

200 .read_probe = mtv_probe,

201 .read_header = mtv_read_header,

202 .read_packet = mtv_read_packet,

203 };

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