1 /*
2 * MxPEG clip file demuxer
3 * Copyright (c) 2010 Anatoly Nenashev
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 */
21
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/internal.h"
24 #include "libavutil/intreadwrite.h"
25 #include "libavcodec/mjpeg.h"
26 #include "avformat.h"
27 #include "internal.h"
28 #include "avio.h"
29
30 #define DEFAULT_PACKET_SIZE 1024
31 #define OVERREAD_SIZE 3
32
33 typedef struct MXGContext {
34 uint8_t *buffer;
35 uint8_t *buffer_ptr;
36 uint8_t *soi_ptr;
37 unsigned int buffer_size;
38 int64_t dts;
39 unsigned int cache_size;
40 } MXGContext;
41
mxg_read_header(AVFormatContext * s)42 static int mxg_read_header(AVFormatContext *s)
43 {
44 AVStream *video_st, *audio_st;
45 MXGContext *mxg = s->priv_data;
46
47 /* video parameters will be extracted from the compressed bitstream */
48 video_st = avformat_new_stream(s, NULL);
49 if (!video_st)
50 return AVERROR(ENOMEM);
51 video_st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
52 video_st->codecpar->codec_id = AV_CODEC_ID_MXPEG;
53 avpriv_set_pts_info(video_st, 64, 1, 1000000);
54
55 audio_st = avformat_new_stream(s, NULL);
56 if (!audio_st)
57 return AVERROR(ENOMEM);
58 audio_st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
59 audio_st->codecpar->codec_id = AV_CODEC_ID_PCM_ALAW;
60 audio_st->codecpar->channels = 1;
61 audio_st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
62 audio_st->codecpar->sample_rate = 8000;
63 audio_st->codecpar->bits_per_coded_sample = 8;
64 audio_st->codecpar->block_align = 1;
65 avpriv_set_pts_info(audio_st, 64, 1, 1000000);
66
67 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
68 mxg->buffer_size = 0;
69 mxg->dts = AV_NOPTS_VALUE;
70 mxg->cache_size = 0;
71
72 return 0;
73 }
74
mxg_find_startmarker(uint8_t * p,uint8_t * end)75 static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
76 {
77 for (; p < end - 3; p += 4) {
78 uint32_t x = AV_RN32(p);
79
80 if (x & (~(x+0x01010101)) & 0x80808080) {
81 if (p[0] == 0xff) {
82 return p;
83 } else if (p[1] == 0xff) {
84 return p+1;
85 } else if (p[2] == 0xff) {
86 return p+2;
87 } else if (p[3] == 0xff) {
88 return p+3;
89 }
90 }
91 }
92
93 for (; p < end; ++p) {
94 if (*p == 0xff) return p;
95 }
96
97 return end;
98 }
99
mxg_update_cache(AVFormatContext * s,unsigned int cache_size)100 static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
101 {
102 MXGContext *mxg = s->priv_data;
103 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
104 unsigned int soi_pos;
105 uint8_t *buffer;
106 int ret;
107
108 /* reallocate internal buffer */
109 if (current_pos > current_pos + cache_size)
110 return AVERROR(ENOMEM);
111 soi_pos = mxg->soi_ptr - mxg->buffer;
112 buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
113 current_pos + cache_size +
114 AV_INPUT_BUFFER_PADDING_SIZE);
115 if (!buffer)
116 return AVERROR(ENOMEM);
117 mxg->buffer = buffer;
118 mxg->buffer_ptr = mxg->buffer + current_pos;
119 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
120
121 /* get data */
122 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
123 cache_size - mxg->cache_size);
124 if (ret < 0)
125 return ret;
126
127 mxg->cache_size += ret;
128
129 return ret;
130 }
131
mxg_read_packet(AVFormatContext * s,AVPacket * pkt)132 static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
133 {
134 int ret;
135 unsigned int size;
136 uint8_t *startmarker_ptr, *end, *search_end, marker;
137 MXGContext *mxg = s->priv_data;
138
139 while (!avio_feof(s->pb) && !s->pb->error){
140 if (mxg->cache_size <= OVERREAD_SIZE) {
141 /* update internal buffer */
142 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
143 if (ret < 0)
144 return ret;
145 }
146 end = mxg->buffer_ptr + mxg->cache_size;
147
148 /* find start marker - 0xff */
149 if (mxg->cache_size > OVERREAD_SIZE) {
150 search_end = end - OVERREAD_SIZE;
151 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
152 } else {
153 search_end = end;
154 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
155 if (startmarker_ptr >= search_end - 1 ||
156 *(startmarker_ptr + 1) != EOI) break;
157 }
158
159 if (startmarker_ptr != search_end) { /* start marker found */
160 marker = *(startmarker_ptr + 1);
161 mxg->buffer_ptr = startmarker_ptr + 2;
162 mxg->cache_size = end - mxg->buffer_ptr;
163
164 if (marker == SOI) {
165 mxg->soi_ptr = startmarker_ptr;
166 } else if (marker == EOI) {
167 if (!mxg->soi_ptr) {
168 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
169 continue;
170 }
171
172 size = mxg->buffer_ptr - mxg->soi_ptr;
173 ret = av_new_packet(pkt, size);
174 if (ret < 0)
175 return ret;
176 memcpy(pkt->data, mxg->soi_ptr, size);
177
178 pkt->pts = pkt->dts = mxg->dts;
179 pkt->stream_index = 0;
180
181 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
182 if (mxg->cache_size > 0) {
183 memmove(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
184 }
185
186 mxg->buffer_ptr = mxg->buffer;
187 }
188 mxg->soi_ptr = 0;
189
190 return pkt->size;
191 } else if ( (SOF0 <= marker && marker <= SOF15) ||
192 (SOS <= marker && marker <= COM) ) {
193 /* all other markers that start marker segment also contain
194 length value (see specification for JPEG Annex B.1) */
195 size = AV_RB16(mxg->buffer_ptr);
196 if (size < 2)
197 return AVERROR(EINVAL);
198
199 if (mxg->cache_size < size) {
200 ret = mxg_update_cache(s, size);
201 if (ret < 0)
202 return ret;
203 startmarker_ptr = mxg->buffer_ptr - 2;
204 mxg->cache_size = 0;
205 } else {
206 mxg->cache_size -= size;
207 }
208
209 mxg->buffer_ptr += size;
210
211 if (marker == APP13 && size >= 16) { /* audio data */
212 ret = av_new_packet(pkt, size - 14);
213 if (ret < 0)
214 return ret;
215 memcpy(pkt->data, startmarker_ptr + 16, size - 14);
216
217 /* time (GMT) of first sample in usec since 1970, little-endian */
218 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
219 pkt->stream_index = 1;
220
221 if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
222 if (mxg->cache_size > 0) {
223 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
224 }
225 mxg->buffer_ptr = mxg->buffer;
226 }
227
228 return pkt->size;
229 } else if (marker == COM && size >= 18 &&
230 !strncmp(startmarker_ptr + 4, "MXF", 3)) {
231 /* time (GMT) of video frame in usec since 1970, little-endian */
232 mxg->dts = AV_RL64(startmarker_ptr + 12);
233 }
234 }
235 } else {
236 /* start marker not found */
237 mxg->buffer_ptr = search_end;
238 mxg->cache_size = OVERREAD_SIZE;
239 }
240 }
241
242 return AVERROR_EOF;
243 }
244
mxg_close(struct AVFormatContext * s)245 static int mxg_close(struct AVFormatContext *s)
246 {
247 MXGContext *mxg = s->priv_data;
248 av_freep(&mxg->buffer);
249 return 0;
250 }
251
252 AVInputFormat ff_mxg_demuxer = {
253 .name = "mxg",
254 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
255 .priv_data_size = sizeof(MXGContext),
256 .read_header = mxg_read_header,
257 .read_packet = mxg_read_packet,
258 .read_close = mxg_close,
259 .extensions = "mxg",
260 };
261