When I write 100 frames MFCreateFMPEG4MediaSink generates multiple moof+mdats.
How do I know how many frames are in each mdat with out parsing the atoms after it is generated ?
Is there a parameter I can set for MFCreateFMPEG4MediaSink so it forces that many frames.
thanks
Standard FMPEG4 media sink would typically package a few frames per moof box, e.g.
<MovieFragmentBox Size="368" Type="moof" Specification="p12" Container="file" TrackFragments="1">
<MovieFragmentHeaderBox Size="16" Type="mfhd" Version="0" Flags="0" Specification="p12" Container="moof" FragmentSequenceNumber="1"></MovieFragmentHeaderBox>
<TrackFragmentBox Size="344" Type="traf" Specification="p12" Container="moof" >
<TrackFragmentHeaderBox Size="28" Type="tfhd" Version="0" Flags="1" Specification="p12" Container="traf" TrackID="1" BaseDataOffset="1123"></TrackFragmentHeaderBox>
<TrackRunBox Size="308" Type="trun" Version="1" Flags="3841" Specification="p12" Container="traf" SampleCount="18" DataOffset="0">
<TrackRunEntry Duration="1000" Size="48020" CTSOffset="0" SamplePadding="0" Sync="1" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="61722" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="48737" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="49846" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="48625" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="34329" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="21388" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="23109" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="20293" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="22243" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="21375" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="22346" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="21611" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="22510" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="21539" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="22698" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="21864" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
<TrackRunEntry Duration="1000" Size="23394" CTSOffset="0" SamplePadding="0" Sync="0" DegradationPriority="0" IsLeading="0" DependsOn="0" IsDependedOn="0" HasRedundancy="0"/>
</TrackRunBox>
</TrackFragmentBox>
</MovieFragmentBox>
<MediaDataBox Size="555657" Type="mdat" Specification="p12" Container="file" dataSize="555649"></MediaDataBox>
(excerpt from one of files produced by MFCreateFMPEG4MediaSink)
There is no setting to change this behavior. There is no reporting on the chosen value. You need to parse output bitstream to find it out if you need it.