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 MTV_IMAGE_DEFAULT_BPP 16

36 #define MTV_AUDIO_SAMPLING_RATE 44100

38 typedef struct MTVDemuxContext {

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

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

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

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

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

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

46 unsigned int img_width;

47 unsigned int img_height;

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

49 unsigned int video_fps;

50 unsigned int full_segment_size;

52 } MTVDemuxContext;

54 static int mtv_probe(AVProbeData *p)

55 {

56 /* we need at least 57 bytes from the header

57 * to try parsing all required fields

58 */

59 if (p->buf_size < 57)

60 return 0;

62 /* Magic is 'AMV' */

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

64 return 0;

66 /* Audio magic is always MP3 */

67 if (p->buf[43] != 'M' || p->buf[44] != 'P' || p->buf[45] != '3')

68 return 0;

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

71 if(!(p->buf[51] && AV_RL16(&p->buf[52]) | AV_RL16(&p->buf[54])))

72 return 0;

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

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

76 {

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

78 return AVPROBE_SCORE_EXTENSION;

79 else

80 return 0;

81 }

83 /* Image bpp is not an absolutely required

84 * field as we latter claim it should be 16

85 * no matter what. All samples in the wild

86 * are RGB565/555.

87 */

88 if(p->buf[51] != MTV_IMAGE_DEFAULT_BPP)

89 return AVPROBE_SCORE_EXTENSION / 2;

91 /* We had enough data to parse header values

92 * but we expect to be able to get 512 bytes

93 * of header to be sure.

94 */

95 if (p->buf_size < MTV_HEADER_SIZE)

96 return AVPROBE_SCORE_EXTENSION;

98 return AVPROBE_SCORE_MAX;

99 }

100

101 static int mtv_read_header(AVFormatContext *s)

102 {

103 MTVDemuxContext *mtv = s->priv_data;

104 AVIOContext *pb = s->pb;

105 AVStream *st;

106 unsigned int audio_subsegments;

107

108 avio_skip(pb, 3);

109 mtv->file_size = avio_rl32(pb);

110 mtv->segments = avio_rl32(pb);

111 avio_skip(pb, 32);

112 mtv->audio_identifier = avio_rl24(pb);

113 mtv->audio_br = avio_rl16(pb);

114 mtv->img_colorfmt = avio_rl24(pb);

115 mtv->img_bpp = avio_r8(pb);

116 mtv->img_width = avio_rl16(pb);

117 mtv->img_height = avio_rl16(pb);

118 mtv->img_segment_size = avio_rl16(pb);

119

120 /* Assume 16bpp even if claimed otherwise.

121 * We know its going to be RGBG565/555 anyway

122 */

123 if (mtv->img_bpp != MTV_IMAGE_DEFAULT_BPP) {

124 av_log (s, AV_LOG_WARNING, "Header claims %dbpp (!= 16). Ignoring\n",

125 mtv->img_bpp);

126 mtv->img_bpp = MTV_IMAGE_DEFAULT_BPP;

127 }

128

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

130

131 if (!mtv->img_width && mtv->img_height > 0 && mtv->img_bpp >= 8)

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

133 / mtv->img_height;

134

135 if (!mtv->img_height && mtv->img_width > 0 && mtv->img_bpp >= 8)

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

137 / mtv->img_width;

138

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

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

141 return AVERROR_INVALIDDATA;

142 }

143

144 avio_skip(pb, 4);

145 audio_subsegments = avio_rl16(pb);

146

147 if (audio_subsegments == 0) {

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

149 return AVERROR_PATCHWELCOME;

150 }

151

152 mtv->full_segment_size =

153 audio_subsegments * (MTV_AUDIO_PADDING_SIZE + MTV_ASUBCHUNK_DATA_SIZE) +

154 mtv->img_segment_size;

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

156

157 // FIXME Add sanity check here

158

159 // all systems go! init decoders

160

161 // video - raw rgb565

162

163 st = avformat_new_stream(s, NULL);

164 if(!st)

165 return AVERROR(ENOMEM);

166

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

168 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

169 st->codec->codec_id = AV_CODEC_ID_RAWVIDEO;

170 st->codec->pix_fmt = AV_PIX_FMT_RGB565BE;

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

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

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

174 st->codec->extradata_size = 9;

175

176 // audio - mp3

177

178 st = avformat_new_stream(s, NULL);

179 if(!st)

180 return AVERROR(ENOMEM);

181

182 avpriv_set_pts_info(st, 64, 1, MTV_AUDIO_SAMPLING_RATE);

183 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;

184 st->codec->codec_id = AV_CODEC_ID_MP3;

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

186 st->need_parsing = AVSTREAM_PARSE_FULL;

187

188 // Jump over header

189

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

191 return AVERROR(EIO);

192

193 return 0;

194

195 }

196

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

198 {

199 MTVDemuxContext *mtv = s->priv_data;

200 AVIOContext *pb = s->pb;

201 int ret;

202

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

204 {

205 avio_skip(pb, MTV_AUDIO_PADDING_SIZE);

206

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

208 if(ret < 0)

209 return ret;

210

211 pkt->pos -= MTV_AUDIO_PADDING_SIZE;

212 pkt->stream_index = 1;

213

214 }else

215 {

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

217 if(ret < 0)

218 return ret;

219

220 pkt->stream_index = 0;

221 }

222

223 return ret;

224 }

225

226 AVInputFormat ff_mtv_demuxer = {

227 .name = "mtv",

228 .long_name = NULL_IF_CONFIG_SMALL("MTV"),

229 .priv_data_size = sizeof(MTVDemuxContext),

230 .read_probe = mtv_probe,

231 .read_header = mtv_read_header,

232 .read_packet = mtv_read_packet,

233 };

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