There is often a lot of confusion from people using MP4Box to create MP4 files or DASH content with a specific aspect ratio. This confusion often comes from badly-chosen acronyms in the MP4/DASH standards. In this post, we clarify what MP4Box uses and does. Continue reading Aspect Ratios
We’ve recently improved the language tagging in GPAC, and in particular in MP4Box and in MP4Client. This posts gives details about how to use these new features. Continue reading Improved language tagging in GPAC
This post is the first post in a series I’m writing to help you discover the many different ways to handle tracks in MP4 files using MP4Box and other GPAC tools, with a particular focus on three types of tracks: subtitles, metadata and graphics tracks. Let me start in this post with subtitle tracks. Continue reading Subtitling with GPAC
At the request of some people, we have added to GPAC some sample applications demonstrating how to use GPAC to demux MP4 files. They are not full applications, just examples taking some MP4 files as input and displaying some information about the media samples contained in the file.
So far, we have added 3 sample applications:
- a basic demuxer called ‘bmp4demux’ capable of reading and dispatching media access units from fragmented or non-fragmented MP4 files, progressively (i.e. while the file is being written);
- a segment based demux called ‘segmp4demuxer‘ capable of dispatching media units from media segments, where the input data is framed. This is what is used for the DASH support;
- and a more advanced demuxer, called ‘fmp4demux’ capable of dispatching media units in streaming mode (i.e. reclaiming resources once media units have been dispatched), where the input data comes from fragmented mp4 but is not framed, i.e. the data in the buffer passed to the demuxer does not start or end at segment or fragment boundaries.