2 * MxPEG clip file demuxer
3 * Copyright (c) 2010 Anatoly Nenashev
5 * This file is part of Libav.
7 * Libav 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.
12 * Libav 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/intreadwrite.h"
24 #include "libavcodec/mjpeg.h"
29 #define DEFAULT_PACKET_SIZE 1024
30 #define OVERREAD_SIZE 3
32 typedef struct MXGContext {
36 unsigned int buffer_size;
38 unsigned int cache_size;
41 static int mxg_read_header(AVFormatContext *s)
43 AVStream *video_st, *audio_st;
44 MXGContext *mxg = s->priv_data;
46 /* video parameters will be extracted from the compressed bitstream */
47 video_st = avformat_new_stream(s, NULL);
49 return AVERROR(ENOMEM);
50 video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
51 video_st->codec->codec_id = AV_CODEC_ID_MXPEG;
52 avpriv_set_pts_info(video_st, 64, 1, 1000000);
54 audio_st = avformat_new_stream(s, NULL);
56 return AVERROR(ENOMEM);
57 audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
58 audio_st->codec->codec_id = AV_CODEC_ID_PCM_ALAW;
59 audio_st->codec->channels = 1;
60 audio_st->codec->channel_layout = AV_CH_LAYOUT_MONO;
61 audio_st->codec->sample_rate = 8000;
62 audio_st->codec->bits_per_coded_sample = 8;
63 audio_st->codec->block_align = 1;
64 avpriv_set_pts_info(audio_st, 64, 1, 1000000);
66 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
68 mxg->dts = AV_NOPTS_VALUE;
74 static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
76 for (; p < end - 3; p += 4) {
77 uint32_t x = *(uint32_t*)p;
79 if (x & (~(x+0x01010101)) & 0x80808080) {
82 } else if (p[1] == 0xff) {
84 } else if (p[2] == 0xff) {
86 } else if (p[3] == 0xff) {
92 for (; p < end; ++p) {
93 if (*p == 0xff) return p;
99 static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
101 MXGContext *mxg = s->priv_data;
102 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
103 unsigned int soi_pos;
106 /* reallocate internal buffer */
107 if (current_pos > current_pos + cache_size)
108 return AVERROR(ENOMEM);
109 if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
110 mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
111 current_pos + cache_size +
112 FF_INPUT_BUFFER_PADDING_SIZE);
114 return AVERROR(ENOMEM);
115 mxg->buffer_ptr = mxg->buffer + current_pos;
116 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
119 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
120 cache_size - mxg->cache_size);
124 mxg->cache_size += ret;
129 static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
133 uint8_t *startmarker_ptr, *end, *search_end, marker;
134 MXGContext *mxg = s->priv_data;
136 while (!s->pb->eof_reached && !s->pb->error){
137 if (mxg->cache_size <= OVERREAD_SIZE) {
138 /* update internal buffer */
139 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
143 end = mxg->buffer_ptr + mxg->cache_size;
145 /* find start marker - 0xff */
146 if (mxg->cache_size > OVERREAD_SIZE) {
147 search_end = end - OVERREAD_SIZE;
148 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
151 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
152 if (startmarker_ptr >= search_end - 1 ||
153 *(startmarker_ptr + 1) != EOI) break;
156 if (startmarker_ptr != search_end) { /* start marker found */
157 marker = *(startmarker_ptr + 1);
158 mxg->buffer_ptr = startmarker_ptr + 2;
159 mxg->cache_size = end - mxg->buffer_ptr;
162 mxg->soi_ptr = startmarker_ptr;
163 } else if (marker == EOI) {
165 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
169 pkt->pts = pkt->dts = mxg->dts;
170 pkt->stream_index = 0;
171 #if FF_API_DESTRUCT_PACKET
172 pkt->destruct = NULL;
175 pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
176 pkt->data = mxg->soi_ptr;
178 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
179 if (mxg->cache_size > 0) {
180 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
183 mxg->buffer_ptr = mxg->buffer;
188 } else if ( (SOF0 <= marker && marker <= SOF15) ||
189 (SOS <= marker && marker <= COM) ) {
190 /* all other markers that start marker segment also contain
191 length value (see specification for JPEG Annex B.1) */
192 size = AV_RB16(mxg->buffer_ptr);
194 return AVERROR(EINVAL);
196 if (mxg->cache_size < size) {
197 ret = mxg_update_cache(s, size);
200 startmarker_ptr = mxg->buffer_ptr - 2;
203 mxg->cache_size -= size;
206 mxg->buffer_ptr += size;
208 if (marker == APP13 && size >= 16) { /* audio data */
209 /* time (GMT) of first sample in usec since 1970, little-endian */
210 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
211 pkt->stream_index = 1;
212 #if FF_API_DESTRUCT_PACKET
213 pkt->destruct = NULL;
216 pkt->size = size - 14;
217 pkt->data = startmarker_ptr + 16;
219 if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
220 if (mxg->cache_size > 0) {
221 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
223 mxg->buffer_ptr = mxg->buffer;
227 } else if (marker == COM && size >= 18 &&
228 !strncmp(startmarker_ptr + 4, "MXF", 3)) {
229 /* time (GMT) of video frame in usec since 1970, little-endian */
230 mxg->dts = AV_RL64(startmarker_ptr + 12);
234 /* start marker not found */
235 mxg->buffer_ptr = search_end;
236 mxg->cache_size = OVERREAD_SIZE;
243 static int mxg_close(struct AVFormatContext *s)
245 MXGContext *mxg = s->priv_data;
246 av_freep(&mxg->buffer);
250 AVInputFormat ff_mxg_demuxer = {
252 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip"),
253 .priv_data_size = sizeof(MXGContext),
254 .read_header = mxg_read_header,
255 .read_packet = mxg_read_packet,
256 .read_close = mxg_close,