1/*
2 * MxPEG clip file demuxer
3 * Copyright (c) 2010 Anatoly Nenashev
4 *
5 * This file is part of Libav.
6 *
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.
11 *
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.
16 *
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
20 */
21
22#include "libavutil/intreadwrite.h"
23#include "libavcodec/mjpeg.h"
24#include "avformat.h"
25#include "internal.h"
26#include "avio.h"
27
28#define DEFAULT_PACKET_SIZE 1024
29#define OVERREAD_SIZE 3
30
31typedef struct MXGContext {
32    uint8_t *buffer;
33    uint8_t *buffer_ptr;
34    uint8_t *soi_ptr;
35    unsigned int buffer_size;
36    int64_t dts;
37    unsigned int cache_size;
38} MXGContext;
39
40static int mxg_read_header(AVFormatContext *s, AVFormatParameters *ap)
41{
42    AVStream *video_st, *audio_st;
43    MXGContext *mxg = s->priv_data;
44
45    /* video parameters will be extracted from the compressed bitstream */
46    video_st = avformat_new_stream(s, NULL);
47    if (!video_st)
48        return AVERROR(ENOMEM);
49    video_st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
50    video_st->codec->codec_id = CODEC_ID_MXPEG;
51    avpriv_set_pts_info(video_st, 64, 1, 1000000);
52
53    audio_st = avformat_new_stream(s, NULL);
54    if (!audio_st)
55        return AVERROR(ENOMEM);
56    audio_st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
57    audio_st->codec->codec_id = CODEC_ID_PCM_ALAW;
58    audio_st->codec->channels = 1;
59    audio_st->codec->sample_rate = 8000;
60    audio_st->codec->bits_per_coded_sample = 8;
61    audio_st->codec->block_align = 1;
62    avpriv_set_pts_info(audio_st, 64, 1, 1000000);
63
64    mxg->soi_ptr = mxg->buffer_ptr = mxg->buffer = 0;
65    mxg->buffer_size = 0;
66    mxg->dts = AV_NOPTS_VALUE;
67    mxg->cache_size = 0;
68
69    return 0;
70}
71
72static uint8_t* mxg_find_startmarker(uint8_t *p, uint8_t *end)
73{
74    for (; p < end - 3; p += 4) {
75        uint32_t x = *(uint32_t*)p;
76
77        if (x & (~(x+0x01010101)) & 0x80808080) {
78            if (p[0] == 0xff) {
79                return p;
80            } else if (p[1] == 0xff) {
81                return p+1;
82            } else if (p[2] == 0xff) {
83                return p+2;
84            } else if (p[3] == 0xff) {
85                return p+3;
86            }
87        }
88    }
89
90    for (; p < end; ++p) {
91        if (*p == 0xff) return p;
92    }
93
94    return end;
95}
96
97static int mxg_update_cache(AVFormatContext *s, unsigned int cache_size)
98{
99    MXGContext *mxg = s->priv_data;
100    unsigned int current_pos = mxg->buffer_ptr - mxg->buffer;
101    unsigned int soi_pos;
102    int ret;
103
104    /* reallocate internal buffer */
105    if (current_pos > current_pos + cache_size)
106        return AVERROR(ENOMEM);
107    if (mxg->soi_ptr) soi_pos = mxg->soi_ptr - mxg->buffer;
108    mxg->buffer = av_fast_realloc(mxg->buffer, &mxg->buffer_size,
109                                  current_pos + cache_size +
110                                  FF_INPUT_BUFFER_PADDING_SIZE);
111    if (!mxg->buffer)
112        return AVERROR(ENOMEM);
113    mxg->buffer_ptr = mxg->buffer + current_pos;
114    if (mxg->soi_ptr) mxg->soi_ptr = mxg->buffer + soi_pos;
115
116    /* get data */
117    ret = avio_read(s->pb, mxg->buffer_ptr + mxg->cache_size,
118                     cache_size - mxg->cache_size);
119    if (ret < 0)
120        return ret;
121
122    mxg->cache_size += ret;
123
124    return ret;
125}
126
127static int mxg_read_packet(AVFormatContext *s, AVPacket *pkt)
128{
129    int ret;
130    unsigned int size;
131    uint8_t *startmarker_ptr, *end, *search_end, marker;
132    MXGContext *mxg = s->priv_data;
133
134    while (!s->pb->eof_reached && !s->pb->error){
135        if (mxg->cache_size <= OVERREAD_SIZE) {
136            /* update internal buffer */
137            ret = mxg_update_cache(s, DEFAULT_PACKET_SIZE + OVERREAD_SIZE);
138            if (ret < 0)
139                return ret;
140        }
141        end = mxg->buffer_ptr + mxg->cache_size;
142
143        /* find start marker - 0xff */
144        if (mxg->cache_size > OVERREAD_SIZE) {
145            search_end = end - OVERREAD_SIZE;
146            startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
147        } else {
148            search_end = end;
149            startmarker_ptr = mxg_find_startmarker(mxg->buffer_ptr, search_end);
150            if (startmarker_ptr >= search_end - 1 ||
151                *(startmarker_ptr + 1) != EOI) break;
152        }
153
154        if (startmarker_ptr != search_end) { /* start marker found */
155            marker = *(startmarker_ptr + 1);
156            mxg->buffer_ptr = startmarker_ptr + 2;
157            mxg->cache_size = end - mxg->buffer_ptr;
158
159            if (marker == SOI) {
160                mxg->soi_ptr = startmarker_ptr;
161            } else if (marker == EOI) {
162                if (!mxg->soi_ptr) {
163                    av_log(s, AV_LOG_WARNING, "Found EOI before SOI, skipping\n");
164                    continue;
165                }
166
167                pkt->pts = pkt->dts = mxg->dts;
168                pkt->stream_index = 0;
169                pkt->destruct = NULL;
170                pkt->size = mxg->buffer_ptr - mxg->soi_ptr;
171                pkt->data = mxg->soi_ptr;
172
173                if (mxg->soi_ptr - mxg->buffer > mxg->cache_size) {
174                    if (mxg->cache_size > 0) {
175                        memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
176                    }
177
178                    mxg->buffer_ptr = mxg->buffer;
179                }
180                mxg->soi_ptr = 0;
181
182                return pkt->size;
183            } else if ( (SOF0 <= marker && marker <= SOF15) ||
184                        (SOS  <= marker && marker <= COM) ) {
185                /* all other markers that start marker segment also contain
186                   length value (see specification for JPEG Annex B.1) */
187                size = AV_RB16(mxg->buffer_ptr);
188                if (size < 2)
189                    return AVERROR(EINVAL);
190
191                if (mxg->cache_size < size) {
192                    ret = mxg_update_cache(s, size);
193                    if (ret < 0)
194                        return ret;
195                    startmarker_ptr = mxg->buffer_ptr - 2;
196                    mxg->cache_size = 0;
197                } else {
198                    mxg->cache_size -= size;
199                }
200
201                mxg->buffer_ptr += size;
202
203                if (marker == APP13 && size >= 16) { /* audio data */
204                    /* time (GMT) of first sample in usec since 1970, little-endian */
205                    pkt->pts = pkt->dts = AV_RL64(startmarker_ptr + 8);
206                    pkt->stream_index = 1;
207                    pkt->destruct = NULL;
208                    pkt->size = size - 14;
209                    pkt->data = startmarker_ptr + 16;
210
211                    if (startmarker_ptr - mxg->buffer > mxg->cache_size) {
212                        if (mxg->cache_size > 0) {
213                            memcpy(mxg->buffer, mxg->buffer_ptr, mxg->cache_size);
214                        }
215                        mxg->buffer_ptr = mxg->buffer;
216                    }
217
218                    return pkt->size;
219                } else if (marker == COM && size >= 18 &&
220                           !strncmp(startmarker_ptr + 4, "MXF", 3)) {
221                    /* time (GMT) of video frame in usec since 1970, little-endian */
222                    mxg->dts = AV_RL64(startmarker_ptr + 12);
223                }
224            }
225        } else {
226            /* start marker not found */
227            mxg->buffer_ptr = search_end;
228            mxg->cache_size = OVERREAD_SIZE;
229        }
230    }
231
232    return AVERROR_EOF;
233}
234
235static int mxg_close(struct AVFormatContext *s)
236{
237    MXGContext *mxg = s->priv_data;
238    av_freep(&mxg->buffer);
239    return 0;
240}
241
242AVInputFormat ff_mxg_demuxer = {
243    .name = "mxg",
244    .long_name = NULL_IF_CONFIG_SMALL("MxPEG clip file format"),
245    .priv_data_size = sizeof(MXGContext),
246    .read_header = mxg_read_header,
247    .read_packet = mxg_read_packet,
248    .read_close = mxg_close,
249    .extensions = "mxg"
250};
251