February 2006 - NUT-devel - lists.mplayerhq.hu

Info Packets
by Michael Niedermayer 20 Feb '06

20 Feb '06

Hi Currently info packets are list of streams list of name/type/value triplets i would suggest that we change this to first name/type/value is the "name/id" of what is described remander is a list of descriptions and require that any 2 info packets with the same name/id be identical one case where the current variant is unclear is ChapterId=5 StartTime=1min StopTime=2min does this mean Chapter 5 is from 1min to 2min or that the info packet describes the time from 1min to 2min of chapter 5? for my suggestion it would be Chapter 5 --- StartTime=1min StopTime=2min vs. TimeSpan 123 --- Chapter=5 StartTime=1min StopTime=2min the following is the simplest way to store things i could come up with: count v for(i=0; i<count; i++){ x v name vb if(x==0){ type vb value vb }else if(x==1){ type= "UTF-8" value vb }else{ type= "rational" value.num s value.den= x-1 } } -- Michael

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Names in Nut Packets
by Michael Niedermayer 20 Feb '06

20 Feb '06

Hi currently Names are UTF-8, IMHO we should limit them to [a-zA-Z0-9] at least or maybe just [a-z] furthermore its a little tempting to either use the unused bytes for common syllables or store things in 5-6bit per char or does that syllable table need to be extendible but not storeable too? in which case iam obviously not agreeing comments? -- Michael

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info packets/frames
by Oded Shimon 19 Feb '06

19 Feb '06

TotalTime is unecessary thanks to max_pts in index no more null termination of info packets stream_id coded sperately seperate to 4 basic types for extendibility, now we can add new fields without breaking old demuxers more: maybe use null terminated strings instead of vb? The reason I gave 'NULL' as an option for type for basic codes, maybe those 1 or 2 vlc's can take on a different meaning with some other type... Also I consider collapsing rational and float into a single code, with different types. They decode the same, being 2 vlc's... - ods15

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Chapters
by Oded Shimon 19 Feb '06

19 Feb '06

I can't decide a proper way for this... One possibility is this: Info packet 1: ChapterId=1, TrackTime=3min Info packet 2: ChapterId=1, TrackTime=4min Info packet 3: ChapterId=2, TrackTime=3min ... But it seems over complicated. I'd like the ability to do this somehow: Single info packet: Chapters=3min,4min,3min,... (in case it wasn't obvious, all the "3min" stuff I meant as a vlc rational) But this can only be done either with parsable strings, or an array of vlc's. Parsable string is bad, and the current info setup does not allow for an array of vlc's... unless you embed it within a 'vb', which is even worse. Maybe Michael had a point in sorting info fields by "age"... I'd like to not follow the curse of mkv and end up with a container just as complicated. :/ This might be a solution: Single info packet: TrackLength=3min TrackLength=4min TrackLength=3min ... And the order they appear in the info packet is the order of the chapters... It's nice, but it gives significance to the order of the items in the info packet which I am not sure is a good idea. Using "TrackLength1", "TrackLength2", ... Is not good cause it's the same idea as parsable strings... Another note: I'd like to disallow info streams in non live streams.. For any purpose, info packets and chapters can be used. (It should at least be a "SHOULD"...) - ods15

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Welcome...
by Oded Shimon 15 Feb '06

15 Feb '06

hut... hut... is this thing on? OK, mailing list is working :) For all your anonymous enjoyment, you can get latest libnut and nututuils from: svn checkout svn://213.144.138.186/nut/trunk Make sure to read README... You'll also see all commits in this ml.. On to buisness... Spec: 1. Split index The only big problem I see is deciding where to split it, and I doubt if even libnut will support this. It's also weird in regards to index_ptr. I vote against this... If it's local storage, you probably have a big damage chunk, not a single byte one... 2. Frame repetition Well, is there anything to really do about this? I can't think of any way a flag would be useful to the demuxer or player, you can just repeat the frame as is, maybe let the codec layer deal with it. 3. convert_ts overflow Uhhh... 120 years otta be enough for everybody. 4. make 'N' implicit in frame codes (as in, no need to explicit specify it is invalid) Anything else? These are truely the last issues I'm aware of, as far as I'm concerned we can (finally) finalize spec... If anybody has anything, say it now... - ods15

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Spec bug with index
by Oded Shimon 13 Feb '06

13 Feb '06

Heh, I didn't expect any problems when implementing EOR, good thing I did, I found a bug in the spec: for(; j<n && j<syncpoints; j++){ if (!has_keyframe[j][i]) continue A v if(!A){ A v B v eor_pts[j][i] = last_pts + A + B }else B=0 keyframe_pts[j][i] = last_pts + A last_pts += A + B } last_pts is implicitly inited to zero. The first key_pts in the file really have a pts of zero, so 'A' needs to be zero, and still not be EOR. This patch fixes this... On another note, the 'prefix' (mpeg-4/mp3 startcode) is officially off the table? - ods15

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Re: [NUT-devel] Welcome...
by Michael Niedermayer 12 Feb '06

12 Feb '06

Hi someone needs cola ... Reply-To: nut-devel-request(a)mplayerhq.hu ----- Forwarded message from Michael Niedermayer <michaelni(a)gmx.at> ----- Date: Sun, 12 Feb 2006 00:42:47 +0100 From: Michael Niedermayer <michaelni(a)gmx.at> To: nut-devel-request(a)mplayerhq.hu Subject: Re: [NUT-devel] Welcome... Message-ID: <20060211234247.GT3210@MichaelsNB> References: <20060211194141.GQ6600@crate15> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060211194141.GQ6600@crate15> User-Agent: Mutt/1.5.10i Status: RO Hi On Sat, Feb 11, 2006 at 09:41:41PM +0200, Oded Shimon wrote: > hut... hut... is this thing on? > OK, mailing list is working :) > > For all your anonymous enjoyment, you can get latest libnut and nututuils > from: > svn checkout svn://213.144.138.186/nut/trunk > > Make sure to read README... > > You'll also see all commits in this ml.. > > > On to buisness... Spec: > > 1. Split index > The only big problem I see is deciding where to split it, and I doubt if > even libnut will support this. It's also weird in regards to index_ptr. I > vote against this... If it's local storage, you probably have a big damage > chunk, not a single byte one... you dont need a single byte error for this to be usefull, if you loose 10kb in one chunk of a 100kb index you really want to be able to recover as much of the 90kb as you can ... > > 2. Frame repetition > Well, is there anything to really do about this? I can't think of any way a > flag would be useful to the demuxer or player, you can just repeat the > frame as is, maybe let the codec layer deal with it. well, i dont care strongly about that, if you are against it fine then repeated frame == (keyframe && binary identical to last), it means 1 compare pass more for the demuxer if it wants to discard them (like when storing a network stream on reliable media) > > 3. convert_ts overflow > Uhhh... 120 years otta be enough for everybody. agree, we can fix that in 100 years ... [...] > Anything else? These are truely the last issues I'm aware of, as far as I'm > concerned we can (finally) finalize spec... If anybody has anything, say it > now... something crazy :) ive already suggested it long ago and its probably a stupid idea but it might mean big reduction of overhead and iam very curious how much space we could save with it ... give each stream 2 byte sequences in the stream header (like codec_specific_data), one for keyframes one for non-key frames, then for each frame, put the correspong byte sequence before the frame before outputing it from the demuxer :) [...] -- Michael ----- End forwarded message ----- -- Michael

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r62 - trunk/libnut
by ods15＠mplayerhq.hu 12 Feb '06

12 Feb '06

Author: ods15 Date: 2006-02-12 18:56:55 +0100 (Sun, 12 Feb 2006) New Revision: 62 Modified: trunk/libnut/demuxer.c trunk/libnut/muxer.c Log: Sync to spec, implicit 'N' frame code Modified: trunk/libnut/demuxer.c =================================================================== --- trunk/libnut/demuxer.c 2006-02-11 17:20:03 UTC (rev 61) +++ trunk/libnut/demuxer.c 2006-02-12 17:56:55 UTC (rev 62) @@ -240,7 +240,11 @@ } for(j = 0; j < count && i < 256; j++, i++) { - assert(i != 'N' || flag == INVALID_FLAG); + if (i == 'N') { + nut->ft[i].flags = INVALID_FLAG; + j--; + continue; + } nut->ft[i].flags = flag; nut->ft[i].stream_flags = sflag; nut->ft[i].stream_plus1 = stream; Modified: trunk/libnut/muxer.c =================================================================== --- trunk/libnut/muxer.c 2006-02-11 17:20:03 UTC (rev 61) +++ trunk/libnut/muxer.c 2006-02-12 17:56:55 UTC (rev 62) @@ -22,9 +22,7 @@ { 0, 5, 1, 1, 673, 2, 672, 0 }, // used 862 times { 0, 5, 1, 1, 769, 2, 768, 0 }, // used 433 times { 0, 5, 1, 1, 961, 2, 960, 0 }, // used 191 times - { 1, 7, 0, 2, 104, 1, 0, 64 }, // "1.2.0" => 14187 - { 4, 3, 0, 0, 1, 0, 0, 0 }, // invalid 'N' - { 1, 5, 0, 2, 104, 1, 64, 0 }, + { 1, 4, 0, 2, 104, 1, 0, 0 }, // "1.2.0" => 14187 { 1, 4, 0, -1, 42, 1, 0, 0 }, // "1.-1.0" => 5707 { 1, 4, 0, 1, 83, 1, 0, 0 }, // "1.1.0" => 11159 { 1, 4, 1, 1, 11, 1, 0, 0 }, // "1.1.1" => 1409 @@ -315,7 +313,11 @@ else count = mul - size; for(j = 0; j < count && i < 256; j++, i++) { - assert(i != 'N' || flag == INVALID_FLAG); + if (i == 'N') { + nut->ft[i].flags = INVALID_FLAG; + j--; + continue; + } nut->ft[i].flags = flag; nut->ft[i].stream_flags = sflag; nut->ft[i].stream_plus1 = stream;

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r61 - trunk/libnut
by ods15＠mplayerhq.hu 11 Feb '06

11 Feb '06

Author: ods15 Date: 2006-02-11 18:20:03 +0100 (Sat, 11 Feb 2006) New Revision: 61 Modified: trunk/libnut/demuxer.c Log: adding checksum checking in find_syncpoint() Modified: trunk/libnut/demuxer.c =================================================================== --- trunk/libnut/demuxer.c 2006-02-11 17:04:36 UTC (rev 60) +++ trunk/libnut/demuxer.c 2006-02-11 17:20:03 UTC (rev 61) @@ -575,10 +575,25 @@ tmp = (tmp << 8) | *(nut->i->buf_ptr++); if (tmp != SYNCPOINT_STARTCODE) continue; if (res) { + int i, scrap; res->pos = bctello(nut->i) - 8; GET_V(nut->i, res->pts); GET_V(nut->i, tmp); res->back_ptr = (tmp * 8 + 7) << 1; + + CHECK(get_bytes(nut->i, 1, &tmp)); + if (!nut->ft[tmp].stream_plus1) GET_V(nut->i, scrap); + if (!nut->ft[tmp].pts_delta) GET_V(nut->i, scrap); + if (nut->ft[tmp].flags & MSB_CODED_FLAG) GET_V(nut->i, scrap); + if (nut->ft[tmp].flags & STREAM_CODED_FLAG) GET_V(nut->i, scrap); + for (i = 0; i < nut->ft[tmp].reserved; i++) GET_V(nut->i, scrap); + CHECK(get_bytes(nut->i, 4, &tmp)); + + if (tmp != crc32(nut->i->buf_ptr - (bctello(nut->i) - res->pos - 8), bctello(nut->i) - 4 - res->pos - 8)) { + tmp = 0; + nut->i->buf_ptr -= bctello(nut->i) - res->pos - 8; // rewind to right after the startcode + continue; + } } if (!backwards) return 0; else ptr = nut->i->buf_ptr;

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r60 - trunk/libnut
by ods15＠mplayerhq.hu 11 Feb '06

11 Feb '06

Author: ods15 Date: 2006-02-11 18:04:36 +0100 (Sat, 11 Feb 2006) New Revision: 60 Modified: trunk/libnut/demuxer.c trunk/libnut/muxer.c Log: add syncpoint_checksum to muxer and demuxer, fix put_frame_header() Modified: trunk/libnut/demuxer.c =================================================================== --- trunk/libnut/demuxer.c 2006-02-11 16:25:50 UTC (rev 59) +++ trunk/libnut/demuxer.c 2006-02-11 17:04:36 UTC (rev 60) @@ -451,7 +451,7 @@ static int get_packet(nut_context_t * nut, nut_packet_t * pd, int * saw_syncpoint) { int err = 0; - int after_sync = 0; + off_t after_sync = 0; uint64_t tmp; int coded_pts, size_lsb = 0, stream_flags = 0, i; @@ -484,9 +484,9 @@ nut->i->buf_ptr -= 8; return get_packet(nut, pd, saw_syncpoint); } else if (tmp == SYNCPOINT_STARTCODE) { + after_sync = bctello(nut->i); CHECK(get_syncpoint(nut)); CHECK(get_bytes(nut->i, 1, &tmp)); - after_sync = 1; } else { nut->i->buf_ptr -= 7; tmp = 'N'; @@ -523,6 +523,13 @@ for (i = 0; i < nut->ft[tmp].reserved; i++) { int scrap; GET_V(nut->i, scrap); } + if (after_sync) { + uint64_t checksum; + off_t pos = bctello(nut->i); + CHECK(get_bytes(nut->i, 4, &checksum)); + ERROR(checksum != crc32(nut->i->buf_ptr - (bctello(nut->i) - after_sync), pos - after_sync), -ERR_BAD_CHECKSUM); + } + // error checking - max distance ERROR(!after_sync && bctello(nut->i) + pd->len - nut->last_syncpoint > nut->max_distance, -ERR_MAX_DISTANCE); // error checking - max pts distance Modified: trunk/libnut/muxer.c =================================================================== --- trunk/libnut/muxer.c 2006-02-11 16:25:50 UTC (rev 59) +++ trunk/libnut/muxer.c 2006-02-11 17:04:36 UTC (rev 60) @@ -135,7 +135,7 @@ put_data(bc, len, data); } -static void put_syncpoint(nut_context_t * nut, const nut_packet_t * fd) { +static void put_syncpoint(nut_context_t * nut, output_buffer_t * bc) { int i; uint64_t pts = 0; int stream = 0; @@ -176,16 +176,16 @@ } back_ptr = (nut->last_syncpoint - s->s[i].pos) / 8; - put_bytes(nut->o, 8, SYNCPOINT_STARTCODE); - put_v(nut->o, pts * nut->stream_count + stream); - put_v(nut->o, back_ptr); - for (i = 0; i < nut->stream_count; i++) { nut->sc[i].last_pts = convert_ts(nut, pts, stream, i); nut->sc[i].last_key = 0; } - nut->sync_overhead += bctello(nut->o) - nut->last_syncpoint; + put_bytes(bc, 8, SYNCPOINT_STARTCODE); + put_v(bc, pts * nut->stream_count + stream); + put_v(bc, back_ptr); + + nut->sync_overhead += bctello(bc) + 4/*checksum*/; } static int frame_header(nut_context_t * nut, const nut_packet_t * fd, int * rftnum) { @@ -219,36 +219,44 @@ return size; } -static void put_frame_header(nut_context_t * nut, output_buffer_t * bc, const nut_packet_t * fd) { +static int put_frame_header(nut_context_t * nut, output_buffer_t * bc, const nut_packet_t * fd) { stream_context_t * sc = &nut->sc[fd->stream]; int ftnum = -1, coded_pts, pts_delta = fd->pts - sc->last_pts; + int size; if (ABS(pts_delta) < (1 << (sc->msb_pts_shift - 1)) - 1) coded_pts = fd->pts & ((1 << sc->msb_pts_shift) - 1); else coded_pts = fd->pts + (1 << sc->msb_pts_shift); - frame_header(nut, fd, &ftnum); + size = frame_header(nut, fd, &ftnum); put_bytes(bc, 1, ftnum); // frame_code - if (!nut->ft[ftnum].stream_plus1) put_v(nut->o, fd->stream); - if (!nut->ft[ftnum].pts_delta) put_v(nut->o, coded_pts); + if (!nut->ft[ftnum].stream_plus1) put_v(bc, fd->stream); + if (!nut->ft[ftnum].pts_delta) put_v(bc, coded_pts); if (nut->ft[ftnum].flags & MSB_CODED_FLAG) - put_v(nut->o, (fd->len - nut->ft[ftnum].lsb) / nut->ft[ftnum].mul); + put_v(bc, (fd->len - nut->ft[ftnum].lsb) / nut->ft[ftnum].mul); if (nut->ft[ftnum].flags & STREAM_CODED_FLAG) - put_v(nut->o, (fd->flags & 3) ^ nut->ft[ftnum].stream_flags); + put_v(bc, (fd->flags & 3) ^ nut->ft[ftnum].stream_flags); + + return size; } -static void put_frame(nut_context_t * nut, const nut_packet_t * fd, const uint8_t * data) { - off_t start = bctello(nut->o); +static void put_frame(nut_context_t * nut, const nut_packet_t * fd, const uint8_t * data, int write_syncpoint) { + output_buffer_t * tmp = clear_buffer(nut->tmp_buffer); stream_context_t * sc = &nut->sc[fd->stream]; int i; - put_frame_header(nut, nut->o, fd); + if (write_syncpoint) put_syncpoint(nut, tmp); + sc->overhead += put_frame_header(nut, tmp, fd); + + put_data(nut->o, tmp->buf_ptr - tmp->buf, tmp->buf); + + if (write_syncpoint) put_bytes(nut->o, 4, crc32(tmp->buf + 8, tmp->buf_ptr - tmp->buf - 8)); // not including startcode + sc->total_frames++; - sc->overhead += bctello(nut->o) - start; sc->tot_size += fd->len; for (i = 0; i < nut->stream_count; i++) { @@ -450,6 +458,7 @@ void nut_write_frame(nut_context_t * nut, const nut_packet_t * fd, const uint8_t * buf) { stream_context_t * sc = &nut->sc[fd->stream]; + int write_syncpoint = 0; if (bctello(nut->o) > (1 << 23)) { // main header repetition int i = 23; // ### magic value for header repetition @@ -465,9 +474,9 @@ if (ABS((int64_t)fd->pts - (int64_t)sc->last_pts) > sc->max_pts_distance) fprintf(stderr, "%d - %d > %d \n", (int)fd->pts, (int)sc->last_pts, sc->max_pts_distance); if (nut->last_syncpoint < nut->last_headers || ABS((int64_t)fd->pts - (int64_t)sc->last_pts) > sc->max_pts_distance || - bctello(nut->o) - nut->last_syncpoint + fd->len + frame_header(nut, fd, NULL) > nut->max_distance) put_syncpoint(nut, fd); + bctello(nut->o) - nut->last_syncpoint + fd->len + frame_header(nut, fd, NULL) > nut->max_distance) write_syncpoint = 1; - put_frame(nut, fd, buf); + put_frame(nut, fd, buf, write_syncpoint); if ((fd->flags & NUT_KEY_STREAM_FLAG) && !sc->last_key) sc->last_key = fd->pts + 1; if (fd->flags & NUT_EOR_STREAM_FLAG) sc->eor = fd->pts + 1;

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