3 * Copyright (c) 2004 The FFmpeg Project
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
25 //#define DEBUG_DUMP_INDEX // XXX dumbdriving-271.nsv breaks with it commented!!
27 #define CHECK_SUBSEQUENT_NSVS
28 //#define DISABLE_AUDIO
30 /* max bytes to crawl for trying to resync
31 * stupid streaming servers don't start at chunk boundaries...
33 #define NSV_MAX_RESYNC (500*1024)
34 #define NSV_MAX_RESYNC_TRIES 300
37 * First version by Francois Revol - revol@free.fr
39 * (1) http://www.multimedia.cx/nsv-format.txt
40 * seems someone came to the same conclusions as me, and updated it:
41 * (2) http://www.stud.ktu.lt/~vitslav/nsv/nsv-format.txt
42 * http://www.stud.ktu.lt/~vitslav/nsv/
44 * (3) http://ultravox.aol.com/NSVFormat.rtf
46 * (S1) http://www.nullsoft.com/nsv/samples/
47 * http://www.nullsoft.com/nsv/samples/faster.nsv
48 * http://streamripper.sourceforge.net/openbb/read.php?TID=492&page=4
52 * notes on the header (Francois Revol):
54 * It is followed by strings, then a table, but nothing tells
55 * where the table begins according to (1). After checking faster.nsv,
56 * I believe NVSf[16-19] gives the size of the strings data
57 * (that is the offset of the data table after the header).
58 * After checking all samples from (S1) all confirms this.
60 * Then, about NSVf[12-15], faster.nsf has 179700. When veiwing it in VLC,
61 * I noticed there was about 1 NVSs chunk/s, so I ran
62 * strings faster.nsv | grep NSVs | wc -l
63 * which gave me 180. That leads me to think that NSVf[12-15] might be the
64 * file length in milliseconds.
66 * for f in *.nsv; do HTIME="$(od -t x4 "$f" | head -1 | sed 's/.* //')"; echo "'$f' $((0x$HTIME))s = $((0x$HTIME/1000/60)):$((0x$HTIME/1000%60))"; done
67 * except for nstrailer (which doesn't have an NSVf header), it repports correct time.
69 * nsvtrailer.nsv (S1) does not have any NSVf header, only NSVs chunks,
70 * so the header seems to not be mandatory. (for streaming).
72 * index slice duration check (excepts nsvtrailer.nsv):
73 * for f in [^n]*.nsv; do DUR="$(ffmpeg -i "$f" 2>/dev/null | grep 'NSVf duration' | cut -d ' ' -f 4)"; IC="$(ffmpeg -i "$f" 2>/dev/null | grep 'INDEX ENTRIES' | cut -d ' ' -f 2)"; echo "duration $DUR, slite time $(($DUR/$IC))"; done
78 * - handle timestamps !!!
80 * - mime-type in probe()
85 #define PRINT(_v) printf _v
92 uint32_t chunk_tag; /* 'NSVf' */
94 uint32_t file_size; /* max 4GB ??? no one learns anything it seems :^) */
95 uint32_t file_length; //unknown1; /* what about MSB of file_size ? */
96 uint32_t info_strings_size; /* size of the info strings */ //unknown2;
97 uint32_t table_entries;
98 uint32_t table_entries_used; /* the left ones should be -1 */
102 uint32_t chunk_tag; /* 'NSVs' */
103 uint32_t v4cc; /* or 'NONE' */
104 uint32_t a4cc; /* or 'NONE' */
105 uint16_t vwidth; /* assert(vwidth%16==0) */
106 uint16_t vheight; /* assert(vheight%16==0) */
107 uint8_t framerate; /* value = (framerate&0x80)?frtable[frameratex0x7f]:framerate */
111 struct nsv_avchunk_header {
112 uint8_t vchunk_size_lsb;
113 uint16_t vchunk_size_msb; /* value = (vchunk_size_msb << 4) | (vchunk_size_lsb >> 4) */
114 uint16_t achunk_size;
117 struct nsv_pcm_header {
118 uint8_t bits_per_sample;
119 uint8_t channel_count;
120 uint16_t sample_rate;
124 /* variation from avi.h */
125 /*typedef struct CodecTag {
132 #define T_NSVF MKTAG('N', 'S', 'V', 'f') /* file header */
133 #define T_NSVS MKTAG('N', 'S', 'V', 's') /* chunk header */
134 #define T_TOC2 MKTAG('T', 'O', 'C', '2') /* extra index marker */
135 #define T_NONE MKTAG('N', 'O', 'N', 'E') /* null a/v 4CC */
136 #define T_SUBT MKTAG('S', 'U', 'B', 'T') /* subtitle aux data */
137 #define T_ASYN MKTAG('A', 'S', 'Y', 'N') /* async a/v aux marker */
138 #define T_KEYF MKTAG('K', 'E', 'Y', 'F') /* video keyframe aux marker (addition) */
140 #define TB_NSVF MKBETAG('N', 'S', 'V', 'f')
141 #define TB_NSVS MKBETAG('N', 'S', 'V', 's')
143 /* hardcoded stream indexes */
144 #define NSV_ST_VIDEO 0
145 #define NSV_ST_AUDIO 1
146 #define NSV_ST_SUBT 2
159 typedef struct NSVStream {
160 int frame_offset; /* current frame (video) or byte (audio) counter
161 (used to compute the pts) */
164 int sample_size; /* audio only data */
167 int new_frame_offset; /* temporary storage (used during seek) */
168 int cum_len; /* temporary storage (used during seek) */
174 uint32_t *nsvs_file_offset;
176 enum NSVStatus state;
177 AVPacket ahead[2]; /* [v, a] if .data is !NULL there is something */
181 uint16_t vwidth, vheight;
183 AVRational framerate;
184 //DVDemuxContext* dv_demux;
187 static const AVCodecTag nsv_codec_video_tags[] = {
188 { CODEC_ID_VP3, MKTAG('V', 'P', '3', ' ') },
189 { CODEC_ID_VP3, MKTAG('V', 'P', '3', '0') },
190 { CODEC_ID_VP3, MKTAG('V', 'P', '3', '1') },
191 { CODEC_ID_VP5, MKTAG('V', 'P', '5', ' ') },
192 { CODEC_ID_VP5, MKTAG('V', 'P', '5', '0') },
193 { CODEC_ID_VP6, MKTAG('V', 'P', '6', ' ') },
194 { CODEC_ID_VP6, MKTAG('V', 'P', '6', '0') },
195 { CODEC_ID_VP6, MKTAG('V', 'P', '6', '1') },
196 { CODEC_ID_VP6, MKTAG('V', 'P', '6', '2') },
198 { CODEC_ID_VP4, MKTAG('V', 'P', '4', ' ') },
199 { CODEC_ID_VP4, MKTAG('V', 'P', '4', '0') },
201 { CODEC_ID_MPEG4, MKTAG('X', 'V', 'I', 'D') }, /* cf sample xvid decoder from nsv_codec_sdk.zip */
202 { CODEC_ID_RAWVIDEO, MKTAG('R', 'G', 'B', '3') },
206 static const AVCodecTag nsv_codec_audio_tags[] = {
207 { CODEC_ID_MP3, MKTAG('M', 'P', '3', ' ') },
208 { CODEC_ID_AAC, MKTAG('A', 'A', 'C', ' ') },
209 { CODEC_ID_AAC, MKTAG('A', 'A', 'C', 'P') },
210 { CODEC_ID_SPEEX, MKTAG('S', 'P', 'X', ' ') },
211 { CODEC_ID_PCM_U16LE, MKTAG('P', 'C', 'M', ' ') },
215 //static int nsv_load_index(AVFormatContext *s);
216 static int nsv_read_chunk(AVFormatContext *s, int fill_header);
219 static void print_tag(const char *str, unsigned int tag, int size)
221 printf("%s: tag=%c%c%c%c\n",
229 /* try to find something we recognize, and set the state accordingly */
230 static int nsv_resync(AVFormatContext *s)
232 NSVContext *nsv = s->priv_data;
233 ByteIOContext *pb = s->pb;
237 PRINT(("%s(), offset = %"PRId64", state = %d\n", __FUNCTION__, url_ftell(pb), nsv->state));
239 //nsv->state = NSV_UNSYNC;
241 for (i = 0; i < NSV_MAX_RESYNC; i++) {
243 PRINT(("NSV EOF\n"));
244 nsv->state = NSV_UNSYNC;
251 PRINT(("NSV resync: [%d] = %02x\n", i, v & 0x0FF));
255 if ((v & 0x0000ffff) == 0xefbe) { /* BEEF */
256 PRINT(("NSV resynced on BEEF after %d bytes\n", i+1));
257 nsv->state = NSV_FOUND_BEEF;
260 /* we read as big endian, thus the MK*BE* */
261 if (v == TB_NSVF) { /* NSVf */
262 PRINT(("NSV resynced on NSVf after %d bytes\n", i+1));
263 nsv->state = NSV_FOUND_NSVF;
266 if (v == MKBETAG('N', 'S', 'V', 's')) { /* NSVs */
267 PRINT(("NSV resynced on NSVs after %d bytes\n", i+1));
268 nsv->state = NSV_FOUND_NSVS;
273 PRINT(("NSV sync lost\n"));
277 static int nsv_parse_NSVf_header(AVFormatContext *s, AVFormatParameters *ap)
279 NSVContext *nsv = s->priv_data;
280 ByteIOContext *pb = s->pb;
281 unsigned int file_size, size;
285 int table_entries_used;
287 PRINT(("%s()\n", __FUNCTION__));
289 nsv->state = NSV_UNSYNC; /* in case we fail */
294 nsv->NSVf_end = size;
296 //s->file_size = (uint32_t)get_le32(pb);
297 file_size = (uint32_t)get_le32(pb);
298 PRINT(("NSV NSVf chunk_size %u\n", size));
299 PRINT(("NSV NSVf file_size %u\n", file_size));
301 nsv->duration = duration = get_le32(pb); /* in ms */
302 PRINT(("NSV NSVf duration %"PRId64" ms\n", duration));
303 // XXX: store it in AVStreams
305 strings_size = get_le32(pb);
306 table_entries = get_le32(pb);
307 table_entries_used = get_le32(pb);
308 PRINT(("NSV NSVf info-strings size: %d, table entries: %d, bis %d\n",
309 strings_size, table_entries, table_entries_used));
313 PRINT(("NSV got header; filepos %"PRId64"\n", url_ftell(pb)));
315 if (strings_size > 0) {
316 char *strings; /* last byte will be '\0' to play safe with str*() */
321 p = strings = av_mallocz(strings_size + 1);
322 endp = strings + strings_size;
323 get_buffer(pb, strings, strings_size);
326 p++; /* strip out spaces */
331 if (!p || p >= endp-2)
336 p = strchr(p, quote);
340 PRINT(("NSV NSVf INFO: %s='%s'\n", token, value));
341 av_metadata_set(&s->metadata, token, value);
348 PRINT(("NSV got infos; filepos %"PRId64"\n", url_ftell(pb)));
350 if (table_entries_used > 0) {
351 nsv->index_entries = table_entries_used;
352 if((unsigned)table_entries >= UINT_MAX / sizeof(uint32_t))
354 nsv->nsvs_file_offset = av_malloc(table_entries * sizeof(uint32_t));
355 #warning "FIXME: Byteswap buffer as needed"
356 get_buffer(pb, (unsigned char *)nsv->nsvs_file_offset, table_entries * sizeof(uint32_t));
359 PRINT(("NSV got index; filepos %"PRId64"\n", url_ftell(pb)));
361 #ifdef DEBUG_DUMP_INDEX
362 #define V(v) ((v<0x20 || v > 127)?'.':v)
364 PRINT(("NSV %d INDEX ENTRIES:\n", table_entries));
365 PRINT(("NSV [dataoffset][fileoffset]\n", table_entries));
366 for (i = 0; i < table_entries; i++) {
368 url_fseek(pb, size + nsv->nsvs_file_offset[i], SEEK_SET);
369 get_buffer(pb, b, 8);
370 PRINT(("NSV [0x%08lx][0x%08lx]: %02x %02x %02x %02x %02x %02x %02x %02x"
371 "%c%c%c%c%c%c%c%c\n",
372 nsv->nsvs_file_offset[i], size + nsv->nsvs_file_offset[i],
373 b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7],
374 V(b[0]), V(b[1]), V(b[2]), V(b[3]), V(b[4]), V(b[5]), V(b[6]), V(b[7]) ));
376 //url_fseek(pb, size, SEEK_SET); /* go back to end of header */
380 url_fseek(pb, nsv->base_offset + size, SEEK_SET); /* required for dumbdriving-271.nsv (2 extra bytes) */
384 nsv->state = NSV_HAS_READ_NSVF;
388 static int nsv_parse_NSVs_header(AVFormatContext *s, AVFormatParameters *ap)
390 NSVContext *nsv = s->priv_data;
391 ByteIOContext *pb = s->pb;
393 uint16_t vwidth, vheight;
394 AVRational framerate;
398 PRINT(("%s()\n", __FUNCTION__));
402 vwidth = get_le16(pb);
403 vheight = get_le16(pb);
406 PRINT(("NSV NSVs framerate code %2x\n", i));
407 if(i&0x80) { /* odd way of giving native framerates from docs */
409 if(t<16) framerate = (AVRational){1, t+1};
410 else framerate = (AVRational){t-15, 1};
413 framerate.num *= 1000;
414 framerate.den *= 1001;
417 if((i&3)==3) framerate.num *= 24;
418 else if((i&3)==2) framerate.num *= 25;
419 else framerate.num *= 30;
422 framerate= (AVRational){i, 1};
424 nsv->avsync = get_le16(pb);
425 nsv->framerate = framerate;
427 print_tag("NSV NSVs vtag", vtag, 0);
428 print_tag("NSV NSVs atag", atag, 0);
429 PRINT(("NSV NSVs vsize %dx%d\n", vwidth, vheight));
432 /* XXX change to ap != NULL ? */
433 if (s->nb_streams == 0) { /* streams not yet published, let's do that */
436 nsv->vwidth = vwidth;
437 nsv->vheight = vwidth;
438 if (vtag != T_NONE) {
439 st = av_new_stream(s, NSV_ST_VIDEO);
443 nst = av_mallocz(sizeof(NSVStream));
447 st->codec->codec_type = CODEC_TYPE_VIDEO;
448 st->codec->codec_tag = vtag;
449 st->codec->codec_id = codec_get_id(nsv_codec_video_tags, vtag);
450 st->codec->width = vwidth;
451 st->codec->height = vheight;
452 st->codec->bits_per_coded_sample = 24; /* depth XXX */
454 av_set_pts_info(st, 64, framerate.den, framerate.num);
456 st->duration = av_rescale(nsv->duration, framerate.num, 1000*framerate.den);
458 if (atag != T_NONE) {
459 #ifndef DISABLE_AUDIO
460 st = av_new_stream(s, NSV_ST_AUDIO);
464 nst = av_mallocz(sizeof(NSVStream));
468 st->codec->codec_type = CODEC_TYPE_AUDIO;
469 st->codec->codec_tag = atag;
470 st->codec->codec_id = codec_get_id(nsv_codec_audio_tags, atag);
472 st->need_parsing = AVSTREAM_PARSE_FULL; /* for PCM we will read a chunk later and put correct info */
474 /* set timebase to common denominator of ms and framerate */
475 av_set_pts_info(st, 64, 1, framerate.num*1000);
477 st->duration = (int64_t)nsv->duration * framerate.num;
480 #ifdef CHECK_SUBSEQUENT_NSVS
482 if (nsv->vtag != vtag || nsv->atag != atag || nsv->vwidth != vwidth || nsv->vheight != vwidth) {
483 PRINT(("NSV NSVs header values differ from the first one!!!\n"));
486 #endif /* CHECK_SUBSEQUENT_NSVS */
489 nsv->state = NSV_HAS_READ_NSVS;
493 nsv->state = NSV_UNSYNC;
497 static int nsv_read_header(AVFormatContext *s, AVFormatParameters *ap)
499 NSVContext *nsv = s->priv_data;
502 PRINT(("%s()\n", __FUNCTION__));
503 PRINT(("filename '%s'\n", s->filename));
505 nsv->state = NSV_UNSYNC;
506 nsv->ahead[0].data = nsv->ahead[1].data = NULL;
508 for (i = 0; i < NSV_MAX_RESYNC_TRIES; i++) {
509 if (nsv_resync(s) < 0)
511 if (nsv->state == NSV_FOUND_NSVF)
512 err = nsv_parse_NSVf_header(s, ap);
513 /* we need the first NSVs also... */
514 if (nsv->state == NSV_FOUND_NSVS) {
515 err = nsv_parse_NSVs_header(s, ap);
516 break; /* we just want the first one */
519 if (s->nb_streams < 1) /* no luck so far */
521 /* now read the first chunk, so we can attempt to decode more info */
522 err = nsv_read_chunk(s, 1);
524 PRINT(("parsed header\n"));
528 static int nsv_read_chunk(AVFormatContext *s, int fill_header)
530 NSVContext *nsv = s->priv_data;
531 ByteIOContext *pb = s->pb;
532 AVStream *st[2] = {NULL, NULL};
536 uint8_t auxcount; /* number of aux metadata, also 4 bits of vsize */
542 PRINT(("%s(%d)\n", __FUNCTION__, fill_header));
544 if (nsv->ahead[0].data || nsv->ahead[1].data)
545 return 0; //-1; /* hey! eat what you've in your plate first! */
551 for (i = 0; i < NSV_MAX_RESYNC_TRIES && nsv->state < NSV_FOUND_NSVS && !err; i++)
555 if (nsv->state == NSV_FOUND_NSVS)
556 err = nsv_parse_NSVs_header(s, NULL);
559 if (nsv->state != NSV_HAS_READ_NSVS && nsv->state != NSV_FOUND_BEEF)
562 auxcount = get_byte(pb);
563 vsize = get_le16(pb);
564 asize = get_le16(pb);
565 vsize = (vsize << 4) | (auxcount >> 4);
567 PRINT(("NSV CHUNK %d aux, %u bytes video, %d bytes audio\n", auxcount, vsize, asize));
569 for (i = 0; i < auxcount; i++) {
570 auxsize = get_le16(pb);
571 auxtag = get_le32(pb);
572 PRINT(("NSV aux data: '%c%c%c%c', %d bytes\n",
574 ((auxtag >> 8) & 0x0ff),
575 ((auxtag >> 16) & 0x0ff),
576 ((auxtag >> 24) & 0x0ff),
578 url_fskip(pb, auxsize);
579 vsize -= auxsize + sizeof(uint16_t) + sizeof(uint32_t); /* that's becoming braindead */
584 if (!vsize && !asize) {
585 nsv->state = NSV_UNSYNC;
586 goto null_chunk_retry;
589 /* map back streams to v,a */
591 st[s->streams[0]->id] = s->streams[0];
593 st[s->streams[1]->id] = s->streams[1];
595 if (vsize/* && st[NSV_ST_VIDEO]*/) {
596 nst = st[NSV_ST_VIDEO]->priv_data;
597 pkt = &nsv->ahead[NSV_ST_VIDEO];
598 av_get_packet(pb, pkt, vsize);
599 pkt->stream_index = st[NSV_ST_VIDEO]->index;//NSV_ST_VIDEO;
600 pkt->dts = nst->frame_offset;
601 pkt->flags |= nsv->state == NSV_HAS_READ_NSVS ? PKT_FLAG_KEY : 0; /* keyframe only likely on a sync frame */
603 for (i = 0; i < MIN(8, vsize); i++)
604 PRINT(("NSV video: [%d] = %02x\n", i, pkt->data[i]));
608 ((NSVStream*)st[NSV_ST_VIDEO]->priv_data)->frame_offset++;
610 if (asize/*st[NSV_ST_AUDIO]*/) {
611 nst = st[NSV_ST_AUDIO]->priv_data;
612 pkt = &nsv->ahead[NSV_ST_AUDIO];
613 /* read raw audio specific header on the first audio chunk... */
614 /* on ALL audio chunks ?? seems so! */
615 if (asize && st[NSV_ST_AUDIO]->codec->codec_tag == MKTAG('P', 'C', 'M', ' ')/* && fill_header*/) {
620 channels = get_byte(pb);
621 samplerate = get_le16(pb);
623 PRINT(("NSV RAWAUDIO: bps %d, nchan %d, srate %d\n", bps, channels, samplerate));
625 st[NSV_ST_AUDIO]->need_parsing = AVSTREAM_PARSE_NONE; /* we know everything */
627 PRINT(("NSV AUDIO bit/sample != 16 (%d)!!!\n", bps));
629 bps /= channels; // ???
631 st[NSV_ST_AUDIO]->codec->codec_id = CODEC_ID_PCM_U8;
632 samplerate /= 4;/* UGH ??? XXX */
634 st[NSV_ST_AUDIO]->codec->channels = channels;
635 st[NSV_ST_AUDIO]->codec->sample_rate = samplerate;
636 PRINT(("NSV RAWAUDIO: bps %d, nchan %d, srate %d\n", bps, channels, samplerate));
639 av_get_packet(pb, pkt, asize);
640 pkt->stream_index = st[NSV_ST_AUDIO]->index;//NSV_ST_AUDIO;
641 pkt->flags |= nsv->state == NSV_HAS_READ_NSVS ? PKT_FLAG_KEY : 0; /* keyframe only likely on a sync frame */
642 if( nsv->state == NSV_HAS_READ_NSVS && st[NSV_ST_VIDEO] ) {
643 /* on a nsvs frame we have new information on a/v sync */
644 pkt->dts = (((NSVStream*)st[NSV_ST_VIDEO]->priv_data)->frame_offset-1);
645 pkt->dts *= (int64_t)1000 * nsv->framerate.den;
646 pkt->dts += (int64_t)nsv->avsync * nsv->framerate.num;
647 PRINT(("NSV AUDIO: sync:%d, dts:%"PRId64, nsv->avsync, pkt->dts));
652 nsv->state = NSV_UNSYNC;
657 static int nsv_read_packet(AVFormatContext *s, AVPacket *pkt)
659 NSVContext *nsv = s->priv_data;
662 PRINT(("%s()\n", __FUNCTION__));
664 /* in case we don't already have something to eat ... */
665 if (nsv->ahead[0].data == NULL && nsv->ahead[1].data == NULL)
666 err = nsv_read_chunk(s, 0);
670 /* now pick one of the plates */
671 for (i = 0; i < 2; i++) {
672 if (nsv->ahead[i].data) {
673 PRINT(("%s: using cached packet[%d]\n", __FUNCTION__, i));
674 /* avoid the cost of new_packet + memcpy(->data) */
675 memcpy(pkt, &nsv->ahead[i], sizeof(AVPacket));
676 nsv->ahead[i].data = NULL; /* we ate that one */
681 /* this restaurant is not approvisionned :^] */
685 static int nsv_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
688 NSVContext *avi = s->priv_data;
698 static int nsv_read_close(AVFormatContext *s)
701 NSVContext *nsv = s->priv_data;
703 if (nsv->index_entries)
704 av_free(nsv->nsvs_file_offset);
708 for(i=0;i<s->nb_streams;i++) {
709 AVStream *st = s->streams[i];
710 NSVStream *ast = st->priv_data;
712 av_free(ast->index_entries);
715 av_free(st->codec->palctrl);
722 static int nsv_probe(AVProbeData *p)
725 // PRINT(("nsv_probe(), buf_size %d\n", p->buf_size));
726 /* check file header */
727 /* streamed files might not have any header */
728 if (p->buf[0] == 'N' && p->buf[1] == 'S' &&
729 p->buf[2] == 'V' && (p->buf[3] == 'f' || p->buf[3] == 's'))
730 return AVPROBE_SCORE_MAX;
731 /* XXX: do streamed files always start at chunk boundary ?? */
732 /* or do we need to search NSVs in the byte stream ? */
733 /* seems the servers don't bother starting clean chunks... */
734 /* sometimes even the first header is at 9KB or something :^) */
735 for (i = 1; i < p->buf_size - 3; i++) {
736 if (p->buf[i+0] == 'N' && p->buf[i+1] == 'S' &&
737 p->buf[i+2] == 'V' && p->buf[i+3] == 's')
738 return AVPROBE_SCORE_MAX-20;
740 /* so we'll have more luck on extension... */
741 if (match_ext(p->filename, "nsv"))
742 return AVPROBE_SCORE_MAX/2;
743 /* FIXME: add mime-type check */
747 AVInputFormat nsv_demuxer = {
749 NULL_IF_CONFIG_SMALL("Nullsoft Streaming Video"),