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 VIDEO_STREAM_INDEX 0
28 #define AUDIO_STREAM_INDEX 1
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, AVFormatParameters *ap)
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 = av_new_stream(s, VIDEO_STREAM_INDEX);
49 return AVERROR(ENOMEM);
50 video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
51 video_st->codec->codec_id = CODEC_ID_MXPEG;
52 av_set_pts_info(video_st, 64, 1, 1000000);
54 audio_st = av_new_stream(s, AUDIO_STREAM_INDEX);
56 return AVERROR(ENOMEM);
57 audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
58 audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
59 audio_st->codec->channels = 1;
60 audio_st->codec->sample_rate = 8000;
61 audio_st->codec->bits_per_coded_sample = 8;
62 audio_st->codec->block_align = 1;
63 av_set_pts_info(audio_st, 64, 1, 1000000);
65 mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
67 mxg->dts = AV_NOPTS_VALUE;
73 static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
75 for (; p < end - 3; p += 4) {
76 uint32_t x = *(uint32_t*)p;
78 if (x & (~(x+0x01010101)) & 0x80808080) {
81 } else if (p[1] == 0xff) {
83 } else if (p[2] == 0xff) {
85 } else if (p[3] == 0xff) {
91 for (; p < end; ++p) {
92 if (*p == 0xff) return p;
98 static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
100 MXGContext *mxg = s->priv_data;
101 unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
102 unsigned int soi_pos;
105 /* reallocate internal buffer */
106 if (current_pos > current_pos + cache_size)
107 return AVERROR(ENOMEM);
108 if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
109 mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
110 current_pos + cache_size +
111 FF_INPUT_BUFFER_PADDING_SIZE);
113 return AVERROR(ENOMEM);
114 mxg->buffer_ptr = mxg->buffer + current_pos;
115 if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
118 ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
119 cache_size - mxg->cache_size);
123 mxg->cache_size += ret;
128 static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
132 uint8_t *startmarker_ptr, *end, *search_end, marker;
133 MXGContext *mxg = s->priv_data;
135 while (!url_feof(s->pb) && !s->pb->error){
136 if (mxg->cache_size <= OVERREAD_SIZE) {
137 /* update internal buffer */
138 ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
142 end = mxg->buffer_ptr + mxg->cache_size;
144 /* find start marker - 0xff */
145 if (mxg->cache_size > OVERREAD_SIZE) {
146 search_end = end - OVERREAD_SIZE;
147 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
150 startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
151 if (startmarker_ptr >= search_end - 1 ||
152 *(startmarker_ptr + 1) != EOI) break;
155 if (startmarker_ptr != search_end) { /* start marker found */
156 marker = *(startmarker_ptr + 1);
157 mxg->buffer_ptr = startmarker_ptr + 2;
158 mxg->cache_size = end - mxg->buffer_ptr;
161 mxg->soi_ptr = startmarker_ptr;
162 } else if (marker == EOI) {
164 av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
168 pkt->pts = pkt->dts = mxg->dts;
169 pkt->stream_index = VIDEO_STREAM_INDEX;
170 pkt->destruct = NULL;
171 pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
172 pkt->data = mxg->soi_ptr;
174 if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
175 if (mxg->cache_size > 0) {
176 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
179 mxg->buffer_ptr = mxg->buffer;
184 } else if ( (SOF0 <= marker && marker <= SOF15) ||
185 (SOS <= marker && marker <= COM) ) {
186 /* all other markers that start marker segment also contain
187 length value (see specification for JPEG Annex B.1) */
188 size = AV_RB16(mxg->buffer_ptr);
190 return AVERROR(EINVAL);
192 if (mxg->cache_size < size) {
193 ret = mxg_update_cache(s, size);
196 startmarker_ptr = mxg->buffer_ptr - 2;
199 mxg->cache_size -= size;
202 mxg->buffer_ptr += size;
204 if (marker == APP13 && size >= 16) { /* audio data */
205 /* time (GMT) of first sample in usec since 1970, little-endian */
206 pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
207 pkt->stream_index = AUDIO_STREAM_INDEX;
208 pkt->destruct = NULL;
209 pkt->size = size - 14;
210 pkt->data = startmarker_ptr + 16;
212 if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
213 if (mxg->cache_size > 0) {
214 memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
216 mxg->buffer_ptr = mxg->buffer;
220 } else if (marker == COM && size >= 18 &&
221 !strncmp(startmarker_ptr + 4, "MXF", 3)) {
222 /* time (GMT) of video frame in usec since 1970, little-endian */
223 mxg->dts = AV_RL64(startmarker_ptr + 12);
227 /* start marker not found */
228 mxg->buffer_ptr = search_end;
229 mxg->cache_size = OVERREAD_SIZE;
236 static int mxg_close(struct AVFormatContext *s)
238 MXGContext *mxg = s->priv_data;
239 av_freep(&mxg->buffer);
243 AVInputFormat ff_mxg_demuxer = {
245 .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"),
246 .priv_data_size = sizeof(MXGContext),
247 .read_header = mxg_read_header,
248 .read_packet = mxg_read_packet,
249 .read_close = mxg_close,