yop.c
Go to the documentation of this file.
1 /*
2  * Psygnosis YOP demuxer
3  *
4  * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
5  * derived from the code by
6  * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.com>
7  *
8  * This file is part of Libav.
9  *
10  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 #include "libavutil/intreadwrite.h"
26 #include "avformat.h"
27 #include "internal.h"
28 
29 typedef struct yop_dec_context {
31 
32  int odd_frame;
37 
38 static int yop_probe(AVProbeData *probe_packet)
39 {
40  if (AV_RB16(probe_packet->buf) == AV_RB16("YO") &&
41  probe_packet->buf[6] &&
42  probe_packet->buf[7] &&
43  !(probe_packet->buf[8] & 1) &&
44  !(probe_packet->buf[10] & 1))
45  return AVPROBE_SCORE_MAX * 3 / 4;
46 
47  return 0;
48 }
49 
51 {
52  YopDecContext *yop = s->priv_data;
53  AVIOContext *pb = s->pb;
54 
55  AVCodecContext *audio_dec, *video_dec;
56  AVStream *audio_stream, *video_stream;
57 
58  int frame_rate, ret;
59 
60  audio_stream = avformat_new_stream(s, NULL);
61  video_stream = avformat_new_stream(s, NULL);
62 
63  // Extra data that will be passed to the decoder
64  video_stream->codec->extradata_size = 8;
65 
66  video_stream->codec->extradata = av_mallocz(video_stream->codec->extradata_size +
68 
69  if (!video_stream->codec->extradata)
70  return AVERROR(ENOMEM);
71 
72  // Audio
73  audio_dec = audio_stream->codec;
74  audio_dec->codec_type = AVMEDIA_TYPE_AUDIO;
75  audio_dec->codec_id = CODEC_ID_ADPCM_IMA_WS;
76  audio_dec->channels = 1;
77  audio_dec->sample_rate = 22050;
78 
79  // Video
80  video_dec = video_stream->codec;
81  video_dec->codec_type = AVMEDIA_TYPE_VIDEO;
82  video_dec->codec_id = CODEC_ID_YOP;
83 
84  avio_skip(pb, 6);
85 
86  frame_rate = avio_r8(pb);
87  yop->frame_size = avio_r8(pb) * 2048;
88  video_dec->width = avio_rl16(pb);
89  video_dec->height = avio_rl16(pb);
90 
91  video_stream->sample_aspect_ratio = (AVRational){1, 2};
92 
93  ret = avio_read(pb, video_dec->extradata, 8);
94  if (ret < 8)
95  return ret < 0 ? ret : AVERROR_EOF;
96 
97  yop->palette_size = video_dec->extradata[0] * 3 + 4;
98  yop->audio_block_length = AV_RL16(video_dec->extradata + 6);
99 
100  // 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920
101  if (yop->audio_block_length < 920 ||
102  yop->audio_block_length + yop->palette_size >= yop->frame_size) {
103  av_log(s, AV_LOG_ERROR, "YOP has invalid header\n");
104  return AVERROR_INVALIDDATA;
105  }
106 
107  avio_seek(pb, 2048, SEEK_SET);
108 
109  avpriv_set_pts_info(video_stream, 32, 1, frame_rate);
110 
111  return 0;
112 }
113 
115 {
116  YopDecContext *yop = s->priv_data;
117  AVIOContext *pb = s->pb;
118 
119  int ret;
120  int actual_video_data_size = yop->frame_size -
121  yop->audio_block_length - yop->palette_size;
122 
123  yop->video_packet.stream_index = 1;
124 
125  if (yop->video_packet.data) {
126  *pkt = yop->video_packet;
127  yop->video_packet.data = NULL;
128  yop->video_packet.size = 0;
129  pkt->data[0] = yop->odd_frame;
130  pkt->flags |= AV_PKT_FLAG_KEY;
131  yop->odd_frame ^= 1;
132  return pkt->size;
133  }
134  ret = av_new_packet(&yop->video_packet,
135  yop->frame_size - yop->audio_block_length);
136  if (ret < 0)
137  return ret;
138 
139  yop->video_packet.pos = avio_tell(pb);
140 
141  ret = avio_read(pb, yop->video_packet.data, yop->palette_size);
142  if (ret < 0) {
143  goto err_out;
144  }else if (ret < yop->palette_size) {
145  ret = AVERROR_EOF;
146  goto err_out;
147  }
148 
149  ret = av_get_packet(pb, pkt, 920);
150  if (ret < 0)
151  goto err_out;
152 
153  // Set position to the start of the frame
154  pkt->pos = yop->video_packet.pos;
155 
156  avio_skip(pb, yop->audio_block_length - ret);
157 
158  ret = avio_read(pb, yop->video_packet.data + yop->palette_size,
159  actual_video_data_size);
160  if (ret < 0)
161  goto err_out;
162  else if (ret < actual_video_data_size)
163  av_shrink_packet(&yop->video_packet, yop->palette_size + ret);
164 
165  // Arbitrarily return the audio data first
166  return yop->audio_block_length;
167 
168 err_out:
169  av_free_packet(&yop->video_packet);
170  return ret;
171 }
172 
174 {
175  YopDecContext *yop = s->priv_data;
176  av_free_packet(&yop->video_packet);
177  return 0;
178 }
179 
180 static int yop_read_seek(AVFormatContext *s, int stream_index,
181  int64_t timestamp, int flags)
182 {
183  YopDecContext *yop = s->priv_data;
184  int64_t frame_pos, pos_min, pos_max;
185  int frame_count;
186 
187  av_free_packet(&yop->video_packet);
188 
189  if (!stream_index)
190  return -1;
191 
192  pos_min = s->data_offset;
193  pos_max = avio_size(s->pb) - yop->frame_size;
194  frame_count = (pos_max - pos_min) / yop->frame_size;
195 
196  timestamp = FFMAX(0, FFMIN(frame_count, timestamp));
197 
198  frame_pos = timestamp * yop->frame_size + pos_min;
199  yop->odd_frame = timestamp & 1;
200 
201  avio_seek(s->pb, frame_pos, SEEK_SET);
202  return 0;
203 }
204 
206  .name = "yop",
207  .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Format"),
208  .priv_data_size = sizeof(YopDecContext),
214  .extensions = "yop",
216 };