- From: Bob Lund <B.Lund@CableLabs.com>
- Date: Mon, 17 Mar 2014 19:23:20 +0000
- To: "Clift, Graham" <Graham.Clift@am.sony.com>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>, "Ota, Takaaki" <Takaaki.Ota@am.sony.com>
- CC: "public-inbandtracks@w3.org" <public-inbandtracks@w3.org>
After rereading the proposed text to resolve the bug, I think it is technically correct. Payload_start_indicator == 1 signifies presence of private sections. Stream_type == 0x05 by definition contains private sections, stream_type == 0x80 - 0xFF may contain private sections. So the UA, upon seeing 0x80 - 0xFF, could wait for indication of private_sections before creating the metadata track. On the other hand, if the UA creates a metadata track for stream_type, say 0xD8, but the stream doesn¡¯t contain private sections there would be no cues generated. Bob On 3/17/14, 1:04 PM, "Bob Lund" <B.Lund@CableLabs.com> wrote: > > >On 3/17/14, 11:49 AM, "Clift, Graham" <Graham.Clift@am.sony.com> wrote: > >>It seems like for TextTrack creation in MPEG-2 TS that detection of the >>metadata private section is only through the stream_type code present in >>the PMT and that the payload_start_indicator==1 is only relevant to >>populating the DataCues that get added to the TextTrack later. > >Yes, you©öre right - the payload_start_indicator should not be used to >determine metadata track; only the stream_type. > >> Hence the patch and the wiki page seem incorrect to me when they suggest >>the payload_start_indicator==1 is used to detect that there is a stream >>type of kind metadata private section. >> >>This also raises another question which is how are the metadata private >>section table cues are generated. If the private section table is >>delivered as a payload split across multiple TS packets then presumably >>the UA must use the payload_start_indicator bit to begin to assemble the >>payload into the single private section table. However, when does the cue >>get created unless the UA knows how many packets to expect? > >The private_section_length field can be used by the UA to know when it©ös >received the last packet for an instance of the table. > >> My understanding is the UA does not know how many packets to expect so >>maybe it generates the cue only when a subsequent >>payload_satart_indicator==1 is detected. However, this could be long past >>the time when this cue is relevant to the media playback time. >> >>Regards >> >>Graham Clift >> >> >> >> >> >> >>-----Original Message----- >>From: Silvia Pfeiffer [mailto:silviapfeiffer1@gmail.com] >>Sent: Monday, March 17, 2014 1:21 AM >>To: Bob Lund >>Cc: public-inbandtracks@w3.org >>Subject: Re: Submitted HTML5 bugs and an MSE observation >> >>On Fri, Mar 14, 2014 at 5:56 AM, Bob Lund <B.Lund@cablelabs.com> wrote: >>> Hi CG, >>> >>> I have submitted the following HTML5 bugs 24986, 24977, 25005 and >>> 25044, reflecting the discussion we've had on the mailing list. >> >>[HTML editor hat on:] >>I've provided feedback and proposed patches in each of these bugs. >>Please review. >> >>Regards, >>Silvia. >> >> >> >
Received on Monday, 17 March 2014 19:23:56 UTC