RTP payload and NAL units

Question

TL;DR:

• Android platform;
• MediaRecorder, using H264 and 3gp;
• MediaRecorder stream to localSocketServer;
• Reading the stream;
  • Skipping the first MPEG header (40 bytes);
  • Searching for NAL units, but nothing

As it is in here http://code.google.com/p/spydroid-ipcamera/source/browse/tags/2.0/trunk/src/net/majorkernelpanic/librtp/H264Packetizer2.java

How to extract the information from the android camera stream to form the NAL header as defined in http://www.ietf.org/rfc/rfc3984.txt?

Thank You

Answer 1

The first NAL unit is after the "mdat" atom in the MPEG4 / H264 header. Then you've got the NAL unit length (likely 4 bytes) followed by the NAL unit header (1 byte).