FFmpeg: libavformat/yop.c Source File

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libavformat

yop.c

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1 /*

2 * Psygnosis YOP demuxer

3 *

5 * derived from the code by

7 *

8 * This file is part of FFmpeg.

9 *

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

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

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

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

14 *

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

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

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

18 * Lesser General Public License for more details.

19 *

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

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

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

23 */

25 #include "libavutil/channel_layout.h"

26 #include "libavutil/intreadwrite.h"

27 #include "avformat.h"

28 #include "internal.h"

30 typedef struct yop_dec_context {

31 AVPacket video_packet;

33 int odd_frame;

34 int frame_size;

35 int audio_block_length;

36 int palette_size;

37 } YopDecContext;

39 static int yop_probe(AVProbeData *probe_packet)

40 {

41 if (AV_RB16(probe_packet->buf) == AV_RB16("YO") &&

42 probe_packet->buf[2]<10 &&

43 probe_packet->buf[3]<10 &&

44 probe_packet->buf[6] &&

45 probe_packet->buf[7] &&

46 !(probe_packet->buf[8] & 1) &&

47 !(probe_packet->buf[10] & 1) &&

48 AV_RL16(probe_packet->buf + 12 + 6) >= 920 &&

49 AV_RL16(probe_packet->buf + 12 + 6) < probe_packet->buf[12] * 3 + 4 + probe_packet->buf[7] * 2048

50 )

51 return AVPROBE_SCORE_MAX * 3 / 4;

53 return 0;

54 }

56 static int yop_read_header(AVFormatContext *s)

57 {

58 YopDecContext *yop = s->priv_data;

59 AVIOContext *pb = s->pb;

61 AVCodecContext *audio_dec, *video_dec;

62 AVStream *audio_stream, *video_stream;

64 int frame_rate, ret;

66 audio_stream = avformat_new_stream(s, NULL);

67 video_stream = avformat_new_stream(s, NULL);

68 if (!audio_stream || !video_stream)

69 return AVERROR(ENOMEM);

71 // Extra data that will be passed to the decoder

72 if (ff_alloc_extradata(video_stream->codec, 8))

73 return AVERROR(ENOMEM);

75 // Audio

76 audio_dec = audio_stream->codec;

77 audio_dec->codec_type = AVMEDIA_TYPE_AUDIO;

78 audio_dec->codec_id = AV_CODEC_ID_ADPCM_IMA_APC;

79 audio_dec->channels = 1;

80 audio_dec->channel_layout = AV_CH_LAYOUT_MONO;

81 audio_dec->sample_rate = 22050;

83 // Video

84 video_dec = video_stream->codec;

85 video_dec->codec_type = AVMEDIA_TYPE_VIDEO;

86 video_dec->codec_id = AV_CODEC_ID_YOP;

88 avio_skip(pb, 6);

90 frame_rate = avio_r8(pb);

91 yop->frame_size = avio_r8(pb) * 2048;

92 video_dec->width = avio_rl16(pb);

93 video_dec->height = avio_rl16(pb);

95 video_stream->sample_aspect_ratio = (AVRational){1, 2};

97 ret = avio_read(pb, video_dec->extradata, 8);

98 if (ret < 8)

99 return ret < 0 ? ret : AVERROR_EOF;

100

101 yop->palette_size = video_dec->extradata[0] * 3 + 4;

102 yop->audio_block_length = AV_RL16(video_dec->extradata + 6);

103

104 video_dec->bit_rate = 8 * (yop->frame_size - yop->audio_block_length) * frame_rate;

105

106 // 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920

107 if (yop->audio_block_length < 920 ||

108 yop->audio_block_length + yop->palette_size >= yop->frame_size) {

109 av_log(s, AV_LOG_ERROR, "YOP has invalid header\n");

110 return AVERROR_INVALIDDATA;

111 }

112

113 avio_seek(pb, 2048, SEEK_SET);

114

115 avpriv_set_pts_info(video_stream, 32, 1, frame_rate);

116

117 return 0;

118 }

119

120 static int yop_read_packet(AVFormatContext *s, AVPacket *pkt)

121 {

122 YopDecContext *yop = s->priv_data;

123 AVIOContext *pb = s->pb;

124

125 int ret;

126 int actual_video_data_size = yop->frame_size -

127 yop->audio_block_length - yop->palette_size;

128

129 yop->video_packet.stream_index = 1;

130

131 if (yop->video_packet.data) {

132 *pkt = yop->video_packet;

133 yop->video_packet.data = NULL;

134 yop->video_packet.buf = NULL;

135 #if FF_API_DESTRUCT_PACKET

136 FF_DISABLE_DEPRECATION_WARNINGS

137 yop->video_packet.destruct = NULL;

138 FF_ENABLE_DEPRECATION_WARNINGS

139 #endif

140 yop->video_packet.size = 0;

141 pkt->data[0] = yop->odd_frame;

142 pkt->flags |= AV_PKT_FLAG_KEY;

143 yop->odd_frame ^= 1;

144 return pkt->size;

145 }

146 ret = av_new_packet(&yop->video_packet,

147 yop->frame_size - yop->audio_block_length);

148 if (ret < 0)

149 return ret;

150

151 yop->video_packet.pos = avio_tell(pb);

152

153 ret = avio_read(pb, yop->video_packet.data, yop->palette_size);

154 if (ret < 0) {

155 goto err_out;

156 }else if (ret < yop->palette_size) {

157 ret = AVERROR_EOF;

158 goto err_out;

159 }

160

161 ret = av_get_packet(pb, pkt, 920);

162 if (ret < 0)

163 goto err_out;

164

165 // Set position to the start of the frame

166 pkt->pos = yop->video_packet.pos;

167

168 avio_skip(pb, yop->audio_block_length - ret);

169

170 ret = avio_read(pb, yop->video_packet.data + yop->palette_size,

171 actual_video_data_size);

172 if (ret < 0)

173 goto err_out;

174 else if (ret < actual_video_data_size)

175 av_shrink_packet(&yop->video_packet, yop->palette_size + ret);

176

177 // Arbitrarily return the audio data first

178 return yop->audio_block_length;

179

180 err_out:

181 av_free_packet(&yop->video_packet);

182 return ret;

183 }

184

185 static int yop_read_close(AVFormatContext *s)

186 {

187 YopDecContext *yop = s->priv_data;

188 av_free_packet(&yop->video_packet);

189 return 0;

190 }

191

192 static int yop_read_seek(AVFormatContext *s, int stream_index,

193 int64_t timestamp, int flags)

194 {

195 YopDecContext *yop = s->priv_data;

196 int64_t frame_pos, pos_min, pos_max;

197 int frame_count;

198

199 if (!stream_index)

200 return -1;

201

202 pos_min = s->internal->data_offset;

203 pos_max = avio_size(s->pb) - yop->frame_size;

204 frame_count = (pos_max - pos_min) / yop->frame_size;

205

206 timestamp = FFMAX(0, FFMIN(frame_count, timestamp));

207

208 frame_pos = timestamp * yop->frame_size + pos_min;

209

210 if (avio_seek(s->pb, frame_pos, SEEK_SET) < 0)

211 return -1;

212

213 av_free_packet(&yop->video_packet);

214 yop->odd_frame = timestamp & 1;

215

216 return 0;

217 }

218

219 AVInputFormat ff_yop_demuxer = {

220 .name = "yop",

221 .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP"),

222 .priv_data_size = sizeof(YopDecContext),

223 .read_probe = yop_probe,

224 .read_header = yop_read_header,

225 .read_packet = yop_read_packet,

226 .read_close = yop_read_close,

227 .read_seek = yop_read_seek,

228 .extensions = "yop",

229 .flags = AVFMT_GENERIC_INDEX,

230 };

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