2 * MxPEG clip file demuxer
3 * Copyright (c) 2010 Anatoly Nenashev
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/intreadwrite.h"
23 #include "libavcodec/mjpeg.h"
27 #define DEFAULT_PACKET_SIZE 1024
28 #define OVERREAD_SIZE 3
30 typedef struct MXGContext {
34 unsigned int buffer_size;
36 unsigned int cache_size;
39 static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap)
41 AVStream *video_st, *audio_st;
42 MXGContext *mxg = s->priv_data;
44 /* video parameters will be extracted from the compressed bitstream */
45 video_st = avformat_new_stream(s, NULL);
47 return AVERROR(ENOMEM);
48 video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
49 video_st->codec->codec_id = CODEC_ID_MXPEG;
50 av_set_pts_info(video_st, 64, 1, 1000000);
52 audio_st = avformat_new_stream(s, NULL);
54 return AVERROR(ENOMEM);
55 audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
56 audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
57 audio_st->codec->channels = 1;
58 audio_st->codec->sample_rate = 8000;
59 audio_st->codec->bits_per_coded_sample = 8;
60 audio_st->codec->block_align = 1;
61 av_set_pts_info(audio_st, 64, 1, 1000000);
63 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
65 mxg->dts = AV_NOPTS_VALUE;
71 static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
73 for (; p < end - 3; p += 4) {
74 uint32_t x = *(uint32_t*)p;
76 if (x & (~(x+0x01010101)) & 0x80808080) {
79 } else if (p[1] == 0xff) {
81 } else if (p[2] == 0xff) {
83 } else if (p[3] == 0xff) {
89 for (; p < end; ++p) {
90 if (*p == 0xff) return p;
96 static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
98 MXGContext *mxg = s->priv_data;
99 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
100 unsigned int soi_pos;
103 /* reallocate internal buffer */
104 if (current_pos > current_pos + cache_size)
105 return AVERROR(ENOMEM);
106 if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
107 mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
108 current_pos + cache_size +
109 FF_INPUT_BUFFER_PADDING_SIZE);
111 return AVERROR(ENOMEM);
112 mxg->buffer_ptr = mxg->buffer + current_pos;
113 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
116 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
117 cache_size - mxg->cache_size);
121 mxg->cache_size += ret;
126 static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
130 uint8_t *startmarker_ptr, *end, *search_end, marker;
131 MXGContext *mxg = s->priv_data;
133 while (!url_feof(s->pb) && !s->pb->error){
134 if (mxg->cache_size <= OVERREAD_SIZE) {
135 /* update internal buffer */
136 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
140 end = mxg->buffer_ptr + mxg->cache_size;
142 /* find start marker - 0xff */
143 if (mxg->cache_size > OVERREAD_SIZE) {
144 search_end = end - OVERREAD_SIZE;
145 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
148 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
149 if (startmarker_ptr >= search_end - 1 ||
150 *(startmarker_ptr + 1) != EOI) break;
153 if (startmarker_ptr != search_end) { /* start marker found */
154 marker = *(startmarker_ptr + 1);
155 mxg->buffer_ptr = startmarker_ptr + 2;
156 mxg->cache_size = end - mxg->buffer_ptr;
159 mxg->soi_ptr = startmarker_ptr;
160 } else if (marker == EOI) {
162 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
166 pkt->pts = pkt->dts = mxg->dts;
167 pkt->stream_index = 0;
168 pkt->destruct = NULL;
169 pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
170 pkt->data = mxg->soi_ptr;
172 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
173 if (mxg->cache_size > 0) {
174 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
177 mxg->buffer_ptr = mxg->buffer;
182 } else if ( (SOF0 <= marker && marker <= SOF15) ||
183 (SOS <= marker && marker <= COM) ) {
184 /* all other markers that start marker segment also contain
185 length value (see specification for JPEG Annex B.1) */
186 size = AV_RB16(mxg->buffer_ptr);
188 return AVERROR(EINVAL);
190 if (mxg->cache_size < size) {
191 ret = mxg_update_cache(s, size);
194 startmarker_ptr = mxg->buffer_ptr - 2;
197 mxg->cache_size -= size;
200 mxg->buffer_ptr += size;
202 if (marker == APP13 && size >= 16) { /* audio data */
203 /* time (GMT) of first sample in usec since 1970, little-endian */
204 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
205 pkt->stream_index = 1;
206 pkt->destruct = NULL;
207 pkt->size = size - 14;
208 pkt->data = startmarker_ptr + 16;
210 if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
211 if (mxg->cache_size > 0) {
212 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
214 mxg->buffer_ptr = mxg->buffer;
218 } else if (marker == COM && size >= 18 &&
219 !strncmp(startmarker_ptr + 4, "MXF", 3)) {
220 /* time (GMT) of video frame in usec since 1970, little-endian */
221 mxg->dts = AV_RL64(startmarker_ptr + 12);
225 /* start marker not found */
226 mxg->buffer_ptr = search_end;
227 mxg->cache_size = OVERREAD_SIZE;
234 static int mxg_close(struct AVFormatContext *s)
236 MXGContext *mxg = s->priv_data;
237 av_freep(&mxg->buffer);
241 AVInputFormat ff_mxg_demuxer = {
243 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"),
244 .priv_data_size = sizeof(MXGContext),
245 .read_header = mxg_read_header,
246 .read_packet = mxg_read_packet,
247 .read_close = mxg_close,