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