# Overview of 3gpapp

3gpapp is an offline utility that manipulates 3GP files. Use 3gpapp to:

- Display information from 3GP files.

- Convert NMS packetized data or raw data to 3GP format.

- Convert 3GP data to NMS packetized or raw format.

- Create a new 3GP file from an existing 3GP file (called rebuilding a file). The new file can have a different file size or playing duration from the original file.

- Perform skew correction while converting NMS packetized data or raw data to 3GP format or while creating a new 3GP file from an existing 3GP file.

- Create a sync point table while converting NMS packetized data or raw data to 3GP format or while creating a new 3GP file from an existing 3GP file.

- Seek a specific time in a 3GP file while converting 3GP data to NMS packetized or raw format.

- Create hint tracks while converting NMS packetized data to 3GP format or creating a new 3GP file from an existing 3GP file.

- Use hint tracks while converting 3GP data to NMS packetized data.

3gpapp handles three types of input and output formats:

- Raw format

- NMS packetized format

- 3GP format

## Raw format

Raw format can be any of the following types of bit streams:

- H.263 baseline profile 0, level 10 - 30 (QCIF, CIF) video elementary bit stream. Video bit streams must conform to ITU-T Recommendation H.263 Annex X as defined in ITU-T Recommendation H.263 1998 and 2000 and 3GPP specifications TS.26.111, TS.26.911, TS.26.140 (H.263).

- H.264 baseline profile level 1 and 2 (QCIF, CIF) video elementary bit stream formatted in the NMS-packetized proprietary format.

Video bit streams must conform to ITU-T Recommendation H.264 and 3GPP specifications TS.26.111, TS.26.911, TS.26.140 (H.264).

Note: Raw video to 3GP format conversion is not supported for the H.264 video codec.

- MPEG-4 simple profile level 0 - 3 (QCIF, CIF) video elementary bit stream. 3gpapp expects an ISO/IEC 14496 simple profile level 0 - 3 bit stream. Time stamping and headers, in particular VOS/VO/VOL headers, should comply with ISO/IEC 14496 and 3GPP TS 26.110 /TS 26.111. This information is needed in the correct format to allow the computation of parameters for 3GP file formatting.

- AMR Narrow-Band IF2 elementary audio bit stream. Audio bit streams must conform to ETSI/AMR, Adaptive Multi-Rate speech codec (AMR), in IF2 framing format, in any of the eight AMR compressed data rates.

## NMS packetized format

NMS packetized format can be any of the previously described raw bit streams, formatted in the NMS packetized proprietary format. For more information about this format, refer to the Video Messaging Server Interface Developer's Reference Manual.

The following table shows the NMS convention for NMS packetized file name extensions generated automatically by 3gpapp:

Extension | Description
.263 | Elementary H.263 bit stream
.n263n | NMS packetized H.263 packetized with RFC 2190
.n263 | NMS packetized H.263 packetized with RFC 2429
.264 | Elementary H.264 bit stream
.n264 | NMS-packetized H.264 packetized with RFC 3984
.m4v | Elementary MPEG-4 bit stream
.nm4v | NMS packetized MPEG-4 packetized with RFC 3016
.amr | AMR raw bit stream
.namr | NMS packetized AMR IF2 packetized with RFC 3267

## 3GP format

The 3GP file format is compliant with the 3GPP TS 26.244 specification and conforms to 3GP file format Basic Profile. A 3GP file contains one video track (either H.263 baseline level 10-30 bit stream, H.264 baseline profile level 1-2 bit stream or MPEG-4 simple profile level 0-3 bit stream), one audio track (IF1 AMR NB audio elementary bit stream), or both.