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extract SRT (subtitles)

--- a/common.h

+++ b/common.h

@@ -10,8 +10,9 @@

 	FmtVp08 = 0x76703038u,

 	FmtVp09 = 0x76703039u,

-	/* a fake one, not supposed to show up in a mp4 */

+	/* fake ones, not supposed to show up in a mp4 */

 	FmtVorbis = 0x766f7262u,

+	FmtSrt = 0x00737274u, /* srt subtitles */

 };

 typedef struct Ebml Ebml;

@@ -29,6 +30,7 @@

 	uvlong duration;

 	uvlong seekpreroll;

 	vlong discardpad;

+	vlong blockdur;

 	struct {

 		char name[16];

 		vlong delay;

@@ -76,6 +78,9 @@

 #pragma varargck type "T" u32int

 int isotypefmt(Fmt *f);

+#pragma varargck type "P" uvlong

+int srttsfmt(Fmt *f);

+

 int isorun(Biobuf *f);

 int ebmlrun(Biobuf *f);

@@ -82,6 +87,7 @@

 u32int crc32(u32int init, u8int *d, ulong len);

 int ivfpacket(Biobuf *out, Packetctx *ctx, Packet *p, int np, uvlong ts);

 int oggpacket(Biobuf *out, Packetctx *ctx, Packet *p, int np, uvlong ts);

+int srtpacket(Biobuf *out, Packetctx *ctx, Packet *p, int np, uvlong ts);

 int ebmlint(Biobuf *f, vlong *out, int isid);

 vlong ebmlel(Biobuf *f, vlong sz, vlong *id, vlong *esz);

 vlong ebmlrawint(Biobuf *f, vlong sz, vlong *dst);

--- a/ebml.c

+++ b/ebml.c

@@ -161,8 +161,7 @@

 			goto err;

 		e->fpacket = ivfpacket;

 		return 0;

-	}

-	if(e->tracktype == 2){

+	}else if(e->tracktype == 2){

 		if(strcmp(c, "vorbis") == 0){

 			e->fmt = FmtVorbis;

 			e->fpacket = oggpacket;

@@ -173,6 +172,12 @@

 			e->fpacket = oggpacket;

 			return 0;

 		}

+	}else if(e->tracktype == 17){

+		if(strcmp(e->codec.name, "S_TEXT/UTF8") == 0){

+			e->fmt = FmtSrt;

+			e->fpacket = srtpacket;

+			return 0;

+		}

 	}

 err:

@@ -231,7 +236,7 @@

 	else if(e->tracktype == 2)

 		Bprint(o, "%s\t%d\t%d", codec(e->codec.name), e->audio.channels, (int)e->audio.samplerate);

 	else if(e->tracktype == 17)

-		Bprint(o, ""); /* FIXME */

+		Bprint(o, "%s", e->codec.name); /* FIXME */

 	else

 		Bprint(o, "???");

 	Bprint(o, "\n");

@@ -258,6 +263,8 @@

 	e.tracknum = -1;

 	duration = 0;

 	for(isebml = 0; left != 0;){

+		if(id == 0x9b)

+			te.blockdur *= timestampscale;

 		if(endtracks > 0 && left < endtracks && trackdump == Nodump){

 			/* early exit */

 			left = 0;

@@ -455,8 +462,8 @@

 				ebmlgetnumber(0x73c5, e.trackuid)

 			else

 				ebmlgetnumber(0x75a2, te.discardpad)

-			//else

-			//	ebmlgetnumber(0x9b, blockdur)

+			else

+				ebmlgetnumber(0x9b, te.blockdur)

 		}

 		if(Bseek(f, sz, 1) < 0)

--- a/main.c

+++ b/main.c

@@ -52,6 +52,7 @@

 	fmtinstall('H', encodefmt);

 	fmtinstall('T', isotypefmt);

+	fmtinstall('P', srttsfmt);

 	Binit(&out, 1, OWRITE);

 	Binit(&stderr, 2, OWRITE);

--- a/mkfile

+++ b/mkfile

@@ -12,6 +12,7 @@

 	ivf.$O\

 	main.$O\

 	ogg.$O\

+	srt.$O\

 HFILES=\

 	common.h\

--- /dev/null

+++ b/srt.c

@@ -1,0 +1,55 @@

+#include <u.h>

+#include <libc.h>

+#include <bio.h>

+#include "common.h"

+

+enum {

+	Timedenum = 1000ULL,

+};

+

+int

+srttsfmt(Fmt *f)

+{

+	char *s, *e, tmp[64];

+	uvlong nsec, sec, msec;

+

+	s = tmp;

+	e = tmp + sizeof(tmp);

+	nsec = va_arg(f->args, uvlong);

+	sec = nsec / 1000000000ULL;

+	msec = nsec/1000000ULL - sec*1000ULL;

+	if(sec >= 3600){

+		s = seprint(s, e, "%02zd:", sec/3600);

+		sec %= 3600;

+	}

+	s = seprint(s, e, "%02zd:", sec/60);

+	sec %= 60;

+	seprint(s, e, "%02zd,%03zd", sec, msec);

+

+	return fmtstrcpy(f, tmp);

+}

+

+int

+srtpacket(Biobuf *out, Packetctx *ctx, Packet *p, int np, uvlong ts)

+{

+	int i, n;

+	uchar *s, *o;

+

+	for(i = 0; i < np; i++, p++){

+		for(s = o = p->data, n = 0; n < p->sz; n++){

+			if(*s == '\r'){

+				if(n+1 >= p->sz || s[1] != '\n')

+					*s = '\n';

+				else{

+					s++;

+					n++;

+				}

+			}

+			*o++ = *s++;

+		}

+		Bprint(out, "%zd\n%P --> %P\n", ++ctx->frid, ts, ts+ctx->blockdur);

+		Bprint(out, "%.*s\n\n", p->sz, (char*)p->data);

+	}

+

+	return 0;

+}

-- 

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