H.264 is a video compression standard used for HD videos. In fact, it’s the most widely-used video codec today. As such, this codec can be incorporated into several container formats like MP4, 3GP, MOV, FLV, and others. Most of the time, it’s encoded with the Advanced Audio Coding (AAC) codec.
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M4A is a filename extension for AAC container format and is developed by Apple Inc. M4A music is bought on the iTunes Store and does not come with DRM protection. In terms of quality, M4A is better than MP3 because it is lossless but still compressed. This means that it occupies less storage space and doesn’t lose quality over time.
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