RE: helix metadata

Erwan,

[Please copy a Helix mailing list when you send me email about Helix. Sometimes I won't be able to get to support email like this
for a while and other engineers on the list may be able to help you sooner.]

>--> I'm interested in retrieving metadata that indicate how to play the
>stream. So, if I'm not wrong, these metadata are retrieved in the stream
>header IHXValues* pHeader, during step 8) CreateStreamHeader(). This is done
>by the File_Format. Then the stream header pHeader is returned to the server
>in step 9) StreamHeaderReady(). In this same step the SDP file is created
>but I can't see in which call... Is the stream info file the SDP file?
>Finally I don't know where all informations are put inside a IHXRegistry.
>

Do you want to playback the media, or just examine the metadata? I was assuming
you wanted to playback AND observe metadata. If you just want to look at 
the metadata, then there is a simpler way of doing that: take a look
at the sample code in datatype/tools/dtdriver/samples/metadata. This uses
the dtdriver framework.

>--> All this concerns the playback of local files. Is this the same for
>streaming from any server? Cause this is what I'm really concerned about.
>

Yes - this works for local and streaming cases.

Eric

=======================================
Eric Hyche ([email protected])
Principal Engineer
RealNetworks, Inc.


>-----Original Message-----
>From: Erwan Gouyette [mailto:[email protected]]
>Sent: Wednesday, May 06, 2009 5:09 AM
>To: [email protected]
>Subject: RE: [Helix-client-dev] helix metadata
>
>
>
>I found out that :
>
>*************************************************************
>  1)In HXFileSource::InitDone (HX_RESULT	 status), there's :
>
>    m_pFFObject->GetFileHeader();
>
>
>  2)In CAACFileFormat::GetFileHeader(), there's :
>
>    m_pFileObject->Seek( 0, FALSE);
>
>
>  3)In HXFileSource::FileHeaderReady ( HX_RESULT status, IHXValues*
>pHeader), there's :
>
>    ContinueWithFileHeader(status, pHeader);
>
>
>  4)In HXFileSource::ContinueWithFileHeader(HX_RESULT status, IHXValues*
>pHeader), there's :
>
>     ProcessFileHeader();
>
>
>  5)In HXFileSource::ProcessFileHeader(void), there's :
>
>    HXSource::ProcessFileHeader();
>    and
>    m_pFFObject->GetStreamHeader(i);
>
>
>  6)In HXSource::ProcessFileHeader(void), there's :
>
>    IHXBuffer*  pTitle = NULL;
>    IHXBuffer*  pAuthor = NULL;
>    IHXBuffer*  pCopyright = NULL;
>    IHXBuffer*  pAbstract = NULL;
>    IHXBuffer*  pDescription = NULL;
>    IHXBuffer*  pLicenseInfo = NULL;
>    IHXBuffer*  pKeywords = NULL;
>    IHXValues*  pValues = NULL;
>    IHXValues*  pMetaInfo = NULL;
>    …
>    pValues->GetPropertyBuffer("Title", pTitle);
>    pValues->GetPropertyBuffer("Author", pAuthor);
>    pValues->GetPropertyBuffer("Copyright", pCopyright);
>    pValues->GetPropertyBuffer("Abstract", pAbstract);
>    pValues->GetPropertyBuffer("Description", pDescription);
>    pValues->GetPropertyBuffer("Keywords", pKeywords);
>    …
>    if (!pTitle)        m_pFileHeader->GetPropertyBuffer("Title", pTitle);
>    if (!pAuthor)       m_pFileHeader->GetPropertyBuffer("Author", pAuthor);
>    if (!pCopyright)    m_pFileHeader->GetPropertyBuffer("Copyright",
>pCopyright);
>    if (!pDescription)  m_pFileHeader->GetPropertyCString("Description",
>pDescription);
>    if (!pAbstract)     m_pFileHeader->GetPropertyCString("Abstract",
>pAbstract);
>    if (!pKeywords)     m_pFileHeader->GetPropertyCString("Keywords",
>pKeywords);
>    …
>    if (pTitle)        pMetaInfo->SetPropertyBuffer("Title", pTitle);
>    if (pAuthor)       pMetaInfo->SetPropertyBuffer("Author", pAuthor);
>    if (pCopyright)    pMetaInfo->SetPropertyBuffer("Copyright",
>pCopyright);
>    if (pDescription)  pMetaInfo->SetPropertyBuffer("Description",
>pDescription);
>    if (pAbstract)     pMetaInfo->SetPropertyBuffer("Abstract", pAbstract);
>    if (pKeywords)     pMetaInfo->SetPropertyBuffer("Keywords", pKeywords);
>
>
>  7)In CAACFileFormat::GetStreamHeader(UINT16 unStreamNumber, there's :
>
>    retVal = CreateStreamHeader(pBuf);
>
>
>  8)In CAACFileFormat::CreateStreamHeader(IHXBuffer * pAACFrame), there's :
>
>    pHdr->SetPropertyULONG32("AvgBitRate", m_ulAvgBitRate);
>    …
>    retVal = m_pFileType->UpdateStreamHeader(pHdr, pAACFrame, m_pContext);
>    …
>    retVal = m_pPayloadFormat->SetStreamHeader(pHdr);
>    …
>    retVal = m_pFormatResponse->StreamHeaderReady(retVal, pHdr);
>
>
>  9)In HXFileSource::StreamHeaderReady(HX_RESULT status, IHXValues*
>pHeader), ther's :
>
>    STREAM_INFO*    pStreamInfo = NULL;
>    …
>    status = HandleSDPData(pHeader);
>    …
>    StreamHeaderReadyExt(pHeader);
>    …
>    return ProcessStreamHeaders(pHeader, pStreamInfo);
>
>
>  10)In HXFileSource::ProcessStreamHeaders(IHXValues* pHeader, STREAM_INFO*&
>pStreamInfo), there's :
>
>    theErr = HXSource::ProcessStreamHeaders(pHeader, pStreamInfo);
>
>
>  11)In HXSource::ProcessStreamHeaders(IHXValues* pHeader, STREAM_INFO*&
>pStreamInfo), there's :
>
>    pHeader->GetPropertyULONG32("StreamNumber",     ulStreamNumber);
>    pHeader->GetPropertyULONG32("AvgBitRate",       ulAvgBitRate);
>    pHeader->GetPropertyULONG32("MaxBitRate",       ulMaxBitRate);
>    pHeader->GetPropertyULONG32("AvgPacketSize",    ulAvgPacketSize);
>    pHeader->GetPropertyULONG32("Predata",          ulPredata);
>    pHeader->GetPropertyULONG32("Duration",         ulDuration);
>    …
>    pStreamInfo->BufferingState().OnStreamHeader(
>    ulStreamNumber,
>    ulPreroll,
>    ulPredata,
>    GetHeaderBOOL(pHeader, "PreDataAtStart"),
>    GetHeaderBOOL(pHeader, "PreDataAfterSeek"),
>    GetHeaderBOOL(pHeader, "PrerollAtStart"),
>    GetHeaderBOOL(pHeader, "PrerollAfterSeek"),
>    ulAvgBitRate,
>    ulMaxBitRate,
>    pMimeType);
>**********************************************************************
>
>
>--> I'm interested in retrieving metadata that indicate how to play the
>stream. So, if I'm not wrong, these metadata are retrieved in the stream
>header IHXValues* pHeader, during step 8) CreateStreamHeader(). This is done
>by the File_Format. Then the stream header pHeader is returned to the server
>in step 9) StreamHeaderReady(). In this same step the SDP file is created
>but I can't see in which call... Is the stream info file the SDP file?
>Finally I don't know where all informations are put inside a IHXRegistry.
>
>--> All this concerns the playback of local files. Is this the same for
>streaming from any server? Cause this is what I'm really concerned about.
>
>Thanks a lot,
>
>Erwan
>
>
>
>-----Message d'origine-----
>De : Eric Hyche [mailto:[email protected]]
>Envoyé : mardi 21 avril 2009 18:18
>À : 'Erwan Gouyette'
>Objet : RE: [Helix-client-dev] helix metadata
>
>In general it works like this:
>
>- file format plugin on the server reads the meta-data out of the media
>  file and puts it in a file header IHXValues which it returns to the
>  server in a IHXFormatResponse::FileHeaderReady() call.
>- Server takes the meta-data from the file header IHXValues and puts
>  it into the SDP which is provided in the RTSP DESCRIBE response.
>- client reads the SDP in the RTSP DESCRIBE response and populates
>  the IHXRegistry with the appropriate meta-data, so that other components
>  (or the application) can read the meta-data from there.
>
>Eric
>
>=======================================
>Eric Hyche ([email protected])
>Principal Engineer
>RealNetworks, Inc.
>
>
>>-----Original Message-----
>>From: Erwan Gouyette [mailto:[email protected]]
>>Sent: Tuesday, April 21, 2009 11:24 AM
>>To: [email protected]
>>Subject: RE: [Helix-client-dev] helix metadata
>>
>>Ok, thank you. But what I don't understand is when and how helix client
>>retrieves the metadata that are coming in a stream. I guess that inside
>data
>>received and stocked in a buffer, it has to retrieve metadata to make the
>>renderer work properly. So, in the source code, where does this happen
>>(HXFileSource::Setup())? I thought a stream header was created and metadata
>>were put inside. Then renderer could access to data through the stream
>>header pointer. Apologies for any inconveniences. Thanks for helping me,
>>
>>Erwan
>>
>>PS: I tried several times and spent hours to build splay but I just can't
>>get through. I could retrieve all sources but I can't go further because of
>>"authenticity of host can't be established". I don't understand why, it
>>makes no sense. But maybe you could indicate me where to look for a debug
>>trace... Thanks
>>
>>
>>-----Message d'origine-----
>>De : Eric Hyche [mailto:[email protected]]
>>Envoyé : mardi 21 avril 2009 15:27
>>À : 'Erwan Gouyette'; [email protected]
>>Objet : RE: [Helix-client-dev] helix metadata
>>
>>The metadata for the currently playing clip is stored in the Helix
>>IHXRegistry. For an example of this, build splay and run it with
>>the -a option. Every 1s or so it will print out its entire registry tree,
>>and you should be able to find the relevant metadata
>>there.
>>
>>Eric
>>
>>=======================================
>>Eric Hyche ([email protected])
>>Principal Engineer
>>RealNetworks, Inc.
>>
>>
>>>-----Original Message-----
>>>From: [email protected]
>>[mailto:[email protected]]
>>>On Behalf Of Erwan Gouyette
>>>Sent: Monday, April 20, 2009 3:54 AM
>>>To: [email protected]
>>>Subject: [Helix-client-dev] helix metadata
>>>
>>>Hello, I'd like to know where (in which function) helix client retrieve
>>metadata about the stream it's
>>>playing?  Thanks,
>>>
>>>
>>>
>>>Erwan
>>
>