[Mp4-tech] Re: PCR Discontinuity Issues

[Mohit Agarwal]

Hi Song,
Is your interpretation an inference as  section 2.4.3.5-
discontinuity_indicator of 
ISO/IEC 13818-1:2000 or H.222.0 never mentions about the PCR_flag.
Is there some other Standard or some other version of H.222.0 which mentions
it .
Is this interpretation valid for ARIB/DVB-H Broadcasted Streams.
Thanks
Mohit
-----Original Message-----
From: mp4-tech-bounces lists.mpegif.org
[mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Song
Sent: Monday, July 17, 2023 7:56 AM
To: mp4-tech lists.mpegif.org
Subject: [Mp4-tech] Re: PCR Discontinuity Issues
Dear Mohit Agarwal
I think which packet contains the valid pcr value should be checked with
PCR_flag in adaptation_field. If PCR_flag set 1, the PCR can be used.
So I think that the sequence can be modified with the following.
...
    <pcr_flag == 1, discontinuity_indicator = 0> 
    <pcr_flag == 0, discontinuity_indicator = 0> // old system time
   <pcr_flag == 0, discontinuity_indicator = 1> // new system time begin
  <pcr_flag == 1, discontinuity_indicator = 1> //  new PCR set.
    <pcr_flag == 1, discontinuity_indicator = 0>  ...
Best Regards.
Song
> 
> Message: 4
> Date: Fri, 14 Jul 2023 15:54:46 +0530
> From: "Mohit Agarwal" <magarwal NeoMagic.com>
> Subject: [Mp4-tech] [MPEG2-SYSTEMS]PCR Discontinuity Issues
> To: <mp4-tech lists.mpegif.org>
> Message-ID: <004601c6a72f$bc76c680$841fa8c0 pcmagarwal>
> Content-Type: text/plain; charset="us-ascii"
> 
> Hi,
>  
> I have a doubt regarding  discontinuity indicator in the case of pcr 
> packets, mentioned in section 2.4.3.5- discontinuity_indicator of 
> H.222.0
>  
> What I interpret from the Standard is:
>  
> <valid_pcr, discontinuity_indicator = 0>  <valid_pcr, 
> discontinuity_indicator = 0>  <invalid_pcr, discontinuity_indicator =
> 1> //do not use this value  <valid_pcr, discontinuity_indicator = 1>
> //use this value  <valid_pcr, discontinuity_indicator = 0>
>    .
>    .
>    .
>  
>  
> The standard also mentions that there can be more than two packets 
> with discontinuity indicator =1.
> But the question in this case is that how does one differentiate which 
> packet contains the valid pcr value???
>  
>  
> Thanks
> Mohit Agarwal

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