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ffmpeg / libavformat / ffmdec.c @ d7fb5a18

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1 de6d9b64 Fabrice Bellard
/*
2 85a6b01d Baptiste Coudurier
 * FFM (ffserver live feed) demuxer
3 66d2ff2a Fabrice Bellard
 * Copyright (c) 2001 Fabrice Bellard.
4 de6d9b64 Fabrice Bellard
 *
5 b78e7197 Diego Biurrun
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8 66d2ff2a Fabrice Bellard
 * modify it under the terms of the GNU Lesser General Public
9
 * License as published by the Free Software Foundation; either
10 b78e7197 Diego Biurrun
 * version 2.1 of the License, or (at your option) any later version.
11 de6d9b64 Fabrice Bellard
 *
12 b78e7197 Diego Biurrun
 * FFmpeg is distributed in the hope that it will be useful,
13 de6d9b64 Fabrice Bellard
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 66d2ff2a Fabrice Bellard
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
16 de6d9b64 Fabrice Bellard
 *
17 66d2ff2a Fabrice Bellard
 * You should have received a copy of the GNU Lesser General Public
18 b78e7197 Diego Biurrun
 * License along with FFmpeg; if not, write to the Free Software
19 5509bffa Diego Biurrun
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 de6d9b64 Fabrice Bellard
 */
21 85a6b01d Baptiste Coudurier
22 de6d9b64 Fabrice Bellard
#include "avformat.h"
23 85a6b01d Baptiste Coudurier
#include "ffm.h"
24 278f987a Baptiste Coudurier
#ifdef CONFIG_FFSERVER
25 8be1c656 Fabrice Bellard
#include <unistd.h>
26 de6d9b64 Fabrice Bellard
27 bc5c918e Diego Biurrun
int64_t ffm_read_write_index(int fd)
28 278f987a Baptiste Coudurier
{
29
    uint8_t buf[8];
30
31
    lseek(fd, 8, SEEK_SET);
32
    read(fd, buf, 8);
33
    return AV_RB64(buf);
34
}
35
36 bc5c918e Diego Biurrun
void ffm_write_write_index(int fd, int64_t pos)
37 278f987a Baptiste Coudurier
{
38
    uint8_t buf[8];
39
    int i;
40
41
    for(i=0;i<8;i++)
42
        buf[i] = (pos >> (56 - i * 8)) & 0xff;
43
    lseek(fd, 8, SEEK_SET);
44
    write(fd, buf, 8);
45
}
46
47 bc5c918e Diego Biurrun
void ffm_set_write_index(AVFormatContext *s, int64_t pos, int64_t file_size)
48 278f987a Baptiste Coudurier
{
49
    FFMContext *ffm = s->priv_data;
50
    ffm->write_index = pos;
51
    ffm->file_size = file_size;
52
}
53
#endif // CONFIG_FFSERVER
54
55 de6d9b64 Fabrice Bellard
static int ffm_is_avail_data(AVFormatContext *s, int size)
56
{
57
    FFMContext *ffm = s->priv_data;
58 bc5c918e Diego Biurrun
    int64_t pos, avail_size;
59 de6d9b64 Fabrice Bellard
    int len;
60
61
    len = ffm->packet_end - ffm->packet_ptr;
62 ba26712b Baptiste Coudurier
    if (size <= len)
63
        return 1;
64 899681cd Björn Axelsson
    pos = url_ftell(s->pb);
65 de6d9b64 Fabrice Bellard
    if (pos == ffm->write_index) {
66
        /* exactly at the end of stream */
67
        return 0;
68
    } else if (pos < ffm->write_index) {
69
        avail_size = ffm->write_index - pos;
70
    } else {
71
        avail_size = (ffm->file_size - pos) + (ffm->write_index - FFM_PACKET_SIZE);
72
    }
73
    avail_size = (avail_size / ffm->packet_size) * (ffm->packet_size - FFM_HEADER_SIZE) + len;
74
    if (size <= avail_size)
75
        return 1;
76
    else
77
        return 0;
78
}
79
80
/* first is true if we read the frame header */
81 4606ac8d Zdenek Kabelac
static int ffm_read_data(AVFormatContext *s,
82 b30bb535 Baptiste Coudurier
                         uint8_t *buf, int size, int header)
83 de6d9b64 Fabrice Bellard
{
84
    FFMContext *ffm = s->priv_data;
85 899681cd Björn Axelsson
    ByteIOContext *pb = s->pb;
86 de6d9b64 Fabrice Bellard
    int len, fill_size, size1, frame_offset;
87
88
    size1 = size;
89
    while (size > 0) {
90
    redo:
91
        len = ffm->packet_end - ffm->packet_ptr;
92 e5ece183 Baptiste Coudurier
        if (len < 0)
93
            return -1;
94 de6d9b64 Fabrice Bellard
        if (len > size)
95
            len = size;
96
        if (len == 0) {
97
            if (url_ftell(pb) == ffm->file_size)
98
                url_fseek(pb, ffm->packet_size, SEEK_SET);
99 5e57424d Philip Gladstone
    retry_read:
100 de6d9b64 Fabrice Bellard
            get_be16(pb); /* PACKET_ID */
101
            fill_size = get_be16(pb);
102 fabb990e Baptiste Coudurier
            ffm->dts = get_be64(pb);
103 de6d9b64 Fabrice Bellard
            frame_offset = get_be16(pb);
104
            get_buffer(pb, ffm->packet, ffm->packet_size - FFM_HEADER_SIZE);
105
            ffm->packet_end = ffm->packet + (ffm->packet_size - FFM_HEADER_SIZE - fill_size);
106 eea2f032 Baptiste Coudurier
            if (ffm->packet_end < ffm->packet || frame_offset < 0)
107 71c32f19 Michael Niedermayer
                return -1;
108 de6d9b64 Fabrice Bellard
            /* if first packet or resynchronization packet, we must
109
               handle it specifically */
110
            if (ffm->first_packet || (frame_offset & 0x8000)) {
111 5e57424d Philip Gladstone
                if (!frame_offset) {
112
                    /* This packet has no frame headers in it */
113
                    if (url_ftell(pb) >= ffm->packet_size * 3) {
114
                        url_fseek(pb, -ffm->packet_size * 2, SEEK_CUR);
115
                        goto retry_read;
116
                    }
117
                    /* This is bad, we cannot find a valid frame header */
118
                    return 0;
119
                }
120 de6d9b64 Fabrice Bellard
                ffm->first_packet = 0;
121 a077f3bc Baptiste Coudurier
                if ((frame_offset & 0x7fff) < FFM_HEADER_SIZE)
122 71c32f19 Michael Niedermayer
                    return -1;
123 de6d9b64 Fabrice Bellard
                ffm->packet_ptr = ffm->packet + (frame_offset & 0x7fff) - FFM_HEADER_SIZE;
124 b30bb535 Baptiste Coudurier
                if (!header)
125 de6d9b64 Fabrice Bellard
                    break;
126
            } else {
127
                ffm->packet_ptr = ffm->packet;
128
            }
129
            goto redo;
130
        }
131
        memcpy(buf, ffm->packet_ptr, len);
132
        buf += len;
133
        ffm->packet_ptr += len;
134
        size -= len;
135 b30bb535 Baptiste Coudurier
        header = 0;
136 de6d9b64 Fabrice Bellard
    }
137
    return size1 - size;
138
}
139
140 4adcbbbe Baptiste Coudurier
//#define DEBUG_SEEK
141
142 a1e01307 Baptiste Coudurier
/* pos is between 0 and file_size - FFM_PACKET_SIZE. It is translated
143
   by the write position inside this function */
144 bc5c918e Diego Biurrun
static void ffm_seek1(AVFormatContext *s, int64_t pos1)
145 a1e01307 Baptiste Coudurier
{
146
    FFMContext *ffm = s->priv_data;
147
    ByteIOContext *pb = s->pb;
148 bc5c918e Diego Biurrun
    int64_t pos;
149 a1e01307 Baptiste Coudurier
150
    pos = pos1 + ffm->write_index;
151
    if (pos >= ffm->file_size)
152
        pos -= (ffm->file_size - FFM_PACKET_SIZE);
153
#ifdef DEBUG_SEEK
154 8999c833 Baptiste Coudurier
    av_log(s, AV_LOG_DEBUG, "seek to %"PRIx64" -> %"PRIx64"\n", pos1, pos);
155 a1e01307 Baptiste Coudurier
#endif
156
    url_fseek(pb, pos, SEEK_SET);
157
}
158
159 bc5c918e Diego Biurrun
static int64_t get_dts(AVFormatContext *s, int64_t pos)
160 979b1a06 Baptiste Coudurier
{
161
    ByteIOContext *pb = s->pb;
162 fabb990e Baptiste Coudurier
    int64_t dts;
163 979b1a06 Baptiste Coudurier
164
    ffm_seek1(s, pos);
165
    url_fskip(pb, 4);
166 fabb990e Baptiste Coudurier
    dts = get_be64(pb);
167 979b1a06 Baptiste Coudurier
#ifdef DEBUG_SEEK
168 8999c833 Baptiste Coudurier
    av_log(s, AV_LOG_DEBUG, "pts=%0.6f\n", pts / 1000000.0);
169 979b1a06 Baptiste Coudurier
#endif
170 fabb990e Baptiste Coudurier
    return dts;
171 979b1a06 Baptiste Coudurier
}
172 de6d9b64 Fabrice Bellard
173 91628427 Philip Gladstone
static void adjust_write_index(AVFormatContext *s)
174
{
175
    FFMContext *ffm = s->priv_data;
176 899681cd Björn Axelsson
    ByteIOContext *pb = s->pb;
177 91628427 Philip Gladstone
    int64_t pts;
178 bc5c918e Diego Biurrun
    //int64_t orig_write_index = ffm->write_index;
179
    int64_t pos_min, pos_max;
180 91628427 Philip Gladstone
    int64_t pts_start;
181 bc5c918e Diego Biurrun
    int64_t ptr = url_ftell(pb);
182 91628427 Philip Gladstone
183
184
    pos_min = 0;
185
    pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
186
187 fabb990e Baptiste Coudurier
    pts_start = get_dts(s, pos_min);
188 91628427 Philip Gladstone
189 fabb990e Baptiste Coudurier
    pts = get_dts(s, pos_max);
190 91628427 Philip Gladstone
191 115329f1 Diego Biurrun
    if (pts - 100000 > pts_start)
192 79292510 Michael Niedermayer
        goto end;
193 91628427 Philip Gladstone
194
    ffm->write_index = FFM_PACKET_SIZE;
195
196 fabb990e Baptiste Coudurier
    pts_start = get_dts(s, pos_min);
197 91628427 Philip Gladstone
198 fabb990e Baptiste Coudurier
    pts = get_dts(s, pos_max);
199 91628427 Philip Gladstone
200
    if (pts - 100000 <= pts_start) {
201
        while (1) {
202 bc5c918e Diego Biurrun
            int64_t newpos;
203 91628427 Philip Gladstone
            int64_t newpts;
204
205
            newpos = ((pos_max + pos_min) / (2 * FFM_PACKET_SIZE)) * FFM_PACKET_SIZE;
206
207
            if (newpos == pos_min)
208
                break;
209
210 fabb990e Baptiste Coudurier
            newpts = get_dts(s, newpos);
211 91628427 Philip Gladstone
212
            if (newpts - 100000 <= pts) {
213
                pos_max = newpos;
214
                pts = newpts;
215
            } else {
216
                pos_min = newpos;
217
            }
218
        }
219
        ffm->write_index += pos_max;
220
    }
221
222 949b1a13 Steve L'Homme
    //printf("Adjusted write index from %"PRId64" to %"PRId64": pts=%0.6f\n", orig_write_index, ffm->write_index, pts / 1000000.);
223 fabb990e Baptiste Coudurier
    //printf("pts range %0.6f - %0.6f\n", get_dts(s, 0) / 1000000. , get_dts(s, ffm->file_size - 2 * FFM_PACKET_SIZE) / 1000000. );
224 91628427 Philip Gladstone
225 79292510 Michael Niedermayer
 end:
226 91628427 Philip Gladstone
    url_fseek(pb, ptr, SEEK_SET);
227
}
228
229
230 de6d9b64 Fabrice Bellard
static int ffm_read_header(AVFormatContext *s, AVFormatParameters *ap)
231
{
232 c9a65ca8 Fabrice Bellard
    FFMContext *ffm = s->priv_data;
233 de6d9b64 Fabrice Bellard
    AVStream *st;
234 899681cd Björn Axelsson
    ByteIOContext *pb = s->pb;
235 de6d9b64 Fabrice Bellard
    AVCodecContext *codec;
236 fa26a29d Fabrice Bellard
    int i, nb_streams;
237 0c1a9eda Zdenek Kabelac
    uint32_t tag;
238 de6d9b64 Fabrice Bellard
239
    /* header */
240
    tag = get_le32(pb);
241
    if (tag != MKTAG('F', 'F', 'M', '1'))
242
        goto fail;
243
    ffm->packet_size = get_be32(pb);
244
    if (ffm->packet_size != FFM_PACKET_SIZE)
245
        goto fail;
246
    ffm->write_index = get_be64(pb);
247
    /* get also filesize */
248
    if (!url_is_streamed(pb)) {
249 a965c478 Aurelien Jacobs
        ffm->file_size = url_fsize(pb);
250 91628427 Philip Gladstone
        adjust_write_index(s);
251 de6d9b64 Fabrice Bellard
    } else {
252 8da9266c Måns Rullgård
        ffm->file_size = (UINT64_C(1) << 63) - 1;
253 de6d9b64 Fabrice Bellard
    }
254
255 fa26a29d Fabrice Bellard
    nb_streams = get_be32(pb);
256 de6d9b64 Fabrice Bellard
    get_be32(pb); /* total bitrate */
257
    /* read each stream */
258 fa26a29d Fabrice Bellard
    for(i=0;i<nb_streams;i++) {
259 75bdb984 Philip Gladstone
        char rc_eq_buf[128];
260
261 fa26a29d Fabrice Bellard
        st = av_new_stream(s, 0);
262 de6d9b64 Fabrice Bellard
        if (!st)
263
            goto fail;
264 26aa0f89 Alex Beregszaszi
        s->streams[i] = st;
265 115329f1 Diego Biurrun
266 e928649b Michael Niedermayer
        av_set_pts_info(st, 64, 1, 1000000);
267 115329f1 Diego Biurrun
268 01f4895c Michael Niedermayer
        codec = st->codec;
269 de6d9b64 Fabrice Bellard
        /* generic info */
270 26aa0f89 Alex Beregszaszi
        codec->codec_id = get_be32(pb);
271
        codec->codec_type = get_byte(pb); /* codec_type */
272 de6d9b64 Fabrice Bellard
        codec->bit_rate = get_be32(pb);
273 26aa0f89 Alex Beregszaszi
        st->quality = get_be32(pb);
274 ccac2e27 Philip Gladstone
        codec->flags = get_be32(pb);
275 22332126 Philip Gladstone
        codec->flags2 = get_be32(pb);
276
        codec->debug = get_be32(pb);
277 de6d9b64 Fabrice Bellard
        /* specific info */
278
        switch(codec->codec_type) {
279
        case CODEC_TYPE_VIDEO:
280 c0df9d75 Michael Niedermayer
            codec->time_base.num = get_be32(pb);
281
            codec->time_base.den = get_be32(pb);
282 de6d9b64 Fabrice Bellard
            codec->width = get_be16(pb);
283
            codec->height = get_be16(pb);
284 20f01548 Philip Gladstone
            codec->gop_size = get_be16(pb);
285 22332126 Philip Gladstone
            codec->pix_fmt = get_be32(pb);
286 20f01548 Philip Gladstone
            codec->qmin = get_byte(pb);
287
            codec->qmax = get_byte(pb);
288
            codec->max_qdiff = get_byte(pb);
289
            codec->qcompress = get_be16(pb) / 10000.0;
290
            codec->qblur = get_be16(pb) / 10000.0;
291 3884a3c3 Philip Gladstone
            codec->bit_rate_tolerance = get_be32(pb);
292 e9a9e0c2 Fabrice Bellard
            codec->rc_eq = av_strdup(get_strz(pb, rc_eq_buf, sizeof(rc_eq_buf)));
293 75bdb984 Philip Gladstone
            codec->rc_max_rate = get_be32(pb);
294
            codec->rc_min_rate = get_be32(pb);
295
            codec->rc_buffer_size = get_be32(pb);
296 7cb8f314 Michael Niedermayer
            codec->i_quant_factor = av_int2dbl(get_be64(pb));
297
            codec->b_quant_factor = av_int2dbl(get_be64(pb));
298
            codec->i_quant_offset = av_int2dbl(get_be64(pb));
299
            codec->b_quant_offset = av_int2dbl(get_be64(pb));
300 75bdb984 Philip Gladstone
            codec->dct_algo = get_be32(pb);
301 22332126 Philip Gladstone
            codec->strict_std_compliance = get_be32(pb);
302
            codec->max_b_frames = get_be32(pb);
303
            codec->luma_elim_threshold = get_be32(pb);
304
            codec->chroma_elim_threshold = get_be32(pb);
305
            codec->mpeg_quant = get_be32(pb);
306
            codec->intra_dc_precision = get_be32(pb);
307
            codec->me_method = get_be32(pb);
308
            codec->mb_decision = get_be32(pb);
309
            codec->nsse_weight = get_be32(pb);
310
            codec->frame_skip_cmp = get_be32(pb);
311 7cb8f314 Michael Niedermayer
            codec->rc_buffer_aggressivity = av_int2dbl(get_be64(pb));
312 038a1243 Alex Beregszaszi
            codec->codec_tag = get_be32(pb);
313 dbedf2aa Baptiste Coudurier
            codec->thread_count = get_byte(pb);
314 de6d9b64 Fabrice Bellard
            break;
315
        case CODEC_TYPE_AUDIO:
316
            codec->sample_rate = get_be32(pb);
317
            codec->channels = get_le16(pb);
318 20f01548 Philip Gladstone
            codec->frame_size = get_le16(pb);
319 de6d9b64 Fabrice Bellard
            break;
320 20f01548 Philip Gladstone
        default:
321 75bdb984 Philip Gladstone
            goto fail;
322 de6d9b64 Fabrice Bellard
        }
323 7080cbe2 Baptiste Coudurier
        if (codec->flags & CODEC_FLAG_GLOBAL_HEADER) {
324
            codec->extradata_size = get_be32(pb);
325
            codec->extradata = av_malloc(codec->extradata_size);
326
            if (!codec->extradata)
327
                return AVERROR(ENOMEM);
328
            get_buffer(pb, codec->extradata, codec->extradata_size);
329
        }
330 de6d9b64 Fabrice Bellard
    }
331
332
    /* get until end of block reached */
333
    while ((url_ftell(pb) % ffm->packet_size) != 0)
334
        get_byte(pb);
335
336
    /* init packet demux */
337
    ffm->packet_ptr = ffm->packet;
338
    ffm->packet_end = ffm->packet;
339
    ffm->frame_offset = 0;
340 fabb990e Baptiste Coudurier
    ffm->dts = 0;
341 de6d9b64 Fabrice Bellard
    ffm->read_state = READ_HEADER;
342
    ffm->first_packet = 1;
343
    return 0;
344
 fail:
345
    for(i=0;i<s->nb_streams;i++) {
346
        st = s->streams[i];
347
        if (st) {
348 1ea4f593 Fabrice Bellard
            av_free(st);
349 de6d9b64 Fabrice Bellard
        }
350
    }
351
    return -1;
352
}
353
354
/* return < 0 if eof */
355
static int ffm_read_packet(AVFormatContext *s, AVPacket *pkt)
356
{
357
    int size;
358
    FFMContext *ffm = s->priv_data;
359 20f01548 Philip Gladstone
    int duration;
360 de6d9b64 Fabrice Bellard
361
    switch(ffm->read_state) {
362
    case READ_HEADER:
363 3c6a9f66 Baptiste Coudurier
        if (!ffm_is_avail_data(s, FRAME_HEADER_SIZE+4)) {
364 8fa36ae0 François Revol
            return AVERROR(EAGAIN);
365 66d2ff2a Fabrice Bellard
        }
366 ff978de4 Baptiste Coudurier
        dprintf(s, "pos=%08"PRIx64" spos=%"PRIx64", write_index=%"PRIx64" size=%"PRIx64"\n",
367 e785efc4 Albert Astals Cid
               url_ftell(s->pb), s->pb->pos, ffm->write_index, ffm->file_size);
368 115329f1 Diego Biurrun
        if (ffm_read_data(s, ffm->header, FRAME_HEADER_SIZE, 1) !=
369 66d2ff2a Fabrice Bellard
            FRAME_HEADER_SIZE)
370 8fa36ae0 François Revol
            return AVERROR(EAGAIN);
371 3c6a9f66 Baptiste Coudurier
        if (ffm->header[1] & FLAG_DTS)
372
            if (ffm_read_data(s, ffm->header+16, 4, 1) != 4)
373
                return AVERROR(EAGAIN);
374 de6d9b64 Fabrice Bellard
#if 0
375 a299832f Baptiste Coudurier
        av_hexdump_log(s, AV_LOG_DEBUG, ffm->header, FRAME_HEADER_SIZE);
376 de6d9b64 Fabrice Bellard
#endif
377
        ffm->read_state = READ_DATA;
378
        /* fall thru */
379
    case READ_DATA:
380 80fb8234 Ronald S. Bultje
        size = AV_RB24(ffm->header + 2);
381 de6d9b64 Fabrice Bellard
        if (!ffm_is_avail_data(s, size)) {
382 8fa36ae0 François Revol
            return AVERROR(EAGAIN);
383 de6d9b64 Fabrice Bellard
        }
384
385 80fb8234 Ronald S. Bultje
        duration = AV_RB24(ffm->header + 5);
386 20f01548 Philip Gladstone
387 de6d9b64 Fabrice Bellard
        av_new_packet(pkt, size);
388
        pkt->stream_index = ffm->header[0];
389 2ea2340e Baptiste Coudurier
        if ((unsigned)pkt->stream_index >= s->nb_streams) {
390
            av_log(s, AV_LOG_ERROR, "invalid stream index %d\n", pkt->stream_index);
391
            av_free_packet(pkt);
392
            ffm->read_state = READ_HEADER;
393
            return AVERROR(EAGAIN);
394
        }
395 899681cd Björn Axelsson
        pkt->pos = url_ftell(s->pb);
396 de6d9b64 Fabrice Bellard
        if (ffm->header[1] & FLAG_KEY_FRAME)
397
            pkt->flags |= PKT_FLAG_KEY;
398 4606ac8d Zdenek Kabelac
399 de6d9b64 Fabrice Bellard
        ffm->read_state = READ_HEADER;
400
        if (ffm_read_data(s, pkt->data, size, 0) != size) {
401
            /* bad case: desynchronized packet. we cancel all the packet loading */
402
            av_free_packet(pkt);
403 8fa36ae0 François Revol
            return AVERROR(EAGAIN);
404 de6d9b64 Fabrice Bellard
        }
405 3c6a9f66 Baptiste Coudurier
        pkt->pts = AV_RB64(ffm->header+8);
406
        if (ffm->header[1] & FLAG_DTS)
407
            pkt->dts = pkt->pts - AV_RB32(ffm->header+16);
408
        else
409
            pkt->dts = pkt->pts;
410 20f01548 Philip Gladstone
        pkt->duration = duration;
411 de6d9b64 Fabrice Bellard
        break;
412
    }
413
    return 0;
414
}
415
416
/* seek to a given time in the file. The file read pointer is
417 aa6b38c2 Diego Biurrun
   positioned at or before pts. XXX: the following code is quite
418 de6d9b64 Fabrice Bellard
   approximative */
419 7b3c1382 Michael Niedermayer
static int ffm_seek(AVFormatContext *s, int stream_index, int64_t wanted_pts, int flags)
420 de6d9b64 Fabrice Bellard
{
421
    FFMContext *ffm = s->priv_data;
422 bc5c918e Diego Biurrun
    int64_t pos_min, pos_max, pos;
423 0c1a9eda Zdenek Kabelac
    int64_t pts_min, pts_max, pts;
424 de6d9b64 Fabrice Bellard
    double pos1;
425
426
#ifdef DEBUG_SEEK
427 8999c833 Baptiste Coudurier
    av_log(s, AV_LOG_DEBUG, "wanted_pts=%0.6f\n", wanted_pts / 1000000.0);
428 de6d9b64 Fabrice Bellard
#endif
429
    /* find the position using linear interpolation (better than
430
       dichotomy in typical cases) */
431
    pos_min = 0;
432
    pos_max = ffm->file_size - 2 * FFM_PACKET_SIZE;
433
    while (pos_min <= pos_max) {
434 fabb990e Baptiste Coudurier
        pts_min = get_dts(s, pos_min);
435
        pts_max = get_dts(s, pos_max);
436 de6d9b64 Fabrice Bellard
        /* linear interpolation */
437 4606ac8d Zdenek Kabelac
        pos1 = (double)(pos_max - pos_min) * (double)(wanted_pts - pts_min) /
438 de6d9b64 Fabrice Bellard
            (double)(pts_max - pts_min);
439 0c1a9eda Zdenek Kabelac
        pos = (((int64_t)pos1) / FFM_PACKET_SIZE) * FFM_PACKET_SIZE;
440 de6d9b64 Fabrice Bellard
        if (pos <= pos_min)
441
            pos = pos_min;
442
        else if (pos >= pos_max)
443
            pos = pos_max;
444 fabb990e Baptiste Coudurier
        pts = get_dts(s, pos);
445 de6d9b64 Fabrice Bellard
        /* check if we are lucky */
446
        if (pts == wanted_pts) {
447
            goto found;
448
        } else if (pts > wanted_pts) {
449
            pos_max = pos - FFM_PACKET_SIZE;
450
        } else {
451
            pos_min = pos + FFM_PACKET_SIZE;
452
        }
453
    }
454 7b3c1382 Michael Niedermayer
    pos = (flags & AVSEEK_FLAG_BACKWARD) ? pos_min : pos_max;
455 de6d9b64 Fabrice Bellard
    if (pos > 0)
456
        pos -= FFM_PACKET_SIZE;
457
 found:
458
    ffm_seek1(s, pos);
459 c07d64c8 Baptiste Coudurier
460
    /* reset read state */
461
    ffm->read_state = READ_HEADER;
462
    ffm->packet_ptr = ffm->packet;
463
    ffm->packet_end = ffm->packet;
464
    ffm->first_packet = 1;
465
466 de6d9b64 Fabrice Bellard
    return 0;
467
}
468
469 07c4ed85 Philip Gladstone
static int ffm_probe(AVProbeData *p)
470
{
471 87e87886 Michael Niedermayer
    if (
472 115329f1 Diego Biurrun
        p->buf[0] == 'F' && p->buf[1] == 'F' && p->buf[2] == 'M' &&
473 66d2ff2a Fabrice Bellard
        p->buf[3] == '1')
474 07c4ed85 Philip Gladstone
        return AVPROBE_SCORE_MAX + 1;
475
    return 0;
476
}
477
478 ff70e601 Måns Rullgård
AVInputFormat ffm_demuxer = {
479 c9a65ca8 Fabrice Bellard
    "ffm",
480 af274fd1 Stefano Sabatini
    NULL_IF_CONFIG_SMALL("FFM (FFserver live feed) format"),
481 66d2ff2a Fabrice Bellard
    sizeof(FFMContext),
482 07c4ed85 Philip Gladstone
    ffm_probe,
483 c9a65ca8 Fabrice Bellard
    ffm_read_header,
484
    ffm_read_packet,
485 9f5d3b13 Baptiste Coudurier
    NULL,
486 c9a65ca8 Fabrice Bellard
    ffm_seek,
487
};