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/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;
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 FF_INPUT_BUFFER_PADDING_SIZE);
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;
121 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
122 cache_size - mxg->cache_size);
126 mxg->cache_size += ret;
131 static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
135 uint8_t *startmarker_ptr, *end, *search_end, marker;
136 MXGContext *mxg = s->priv_data;
138 while (!url_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);
145 end = mxg->buffer_ptr + mxg->cache_size;
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);
153 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
154 if (startmarker_ptr >= search_end - 1 ||
155 *(startmarker_ptr + 1) != EOI) break;
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;
164 mxg->soi_ptr = startmarker_ptr;
165 } else if (marker == EOI) {
167 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
171 pkt->pts = pkt->dts = mxg->dts;
172 pkt->stream_index = 0;
173 #if FF_API_DESTRUCT_PACKET
174 pkt->destruct = NULL;
177 pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
178 pkt->data = mxg->soi_ptr;
180 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
181 if (mxg->cache_size > 0) {
182 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
185 mxg->buffer_ptr = mxg->buffer;
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);
196 return AVERROR(EINVAL);
198 if (mxg->cache_size < size) {
199 ret = mxg_update_cache(s, size);
202 startmarker_ptr = mxg->buffer_ptr - 2;
205 mxg->cache_size -= size;
208 mxg->buffer_ptr += size;
210 if (marker == APP13 && size >= 16) { /* audio data */
211 /* time (GMT) of first sample in usec since 1970, little-endian */
212 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
213 pkt->stream_index = 1;
214 #if FF_API_DESTRUCT_PACKET
215 pkt->destruct = NULL;
218 pkt->size = size - 14;
219 pkt->data = startmarker_ptr + 16;
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);
225 mxg->buffer_ptr = mxg->buffer;
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);
236 /* start marker not found */
237 mxg->buffer_ptr = search_end;
238 mxg->cache_size = OVERREAD_SIZE;
245 static int mxg_close(struct AVFormatContext *s)
247 MXGContext *mxg = s->priv_data;
248 av_freep(&mxg->buffer);
252 AVInputFormat ff_mxg_demuxer = {
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,