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Tuesday, August 16, 2011

DPP Solutions: AV File Formats

As you get into multimedia, the alphabet soup of file formats can be confusing. Here’s a quick reference guide to common file types.



The following is an annotated list of the data file types you may encounter while working with audio/video recorders and editing systems.

Uncompressed Audio Files
WAV: Flexible PCM file based on the Resource Interchange File Format (RIFF) and capable of storing virtually any combination of bit rates and sample frequencies; ideal format for data interchange and storage/archiving; BWF, or Broadcast WAV, adds standardized metadata and timecode references for sample-accurate AV synchronization within recorders and workstations.

AIFF (Apple Interchange File Format): A PCM file similar in structure to WAV; directly compatible with Mac OS, but capable of being read by and output to most audio and video workstations and related applications.

Compressed Audio Files
Audio Codecs: Encoding/decoding schemes capable of producing data-reduced versions of 16/24-bit audio files at variable sample frequencies, either lossy or lossless in format; includes MP3 (Motion Picture Experts Group | Layer 3), QuickTime, Microsoft Windows Media Audio, Apple Advanced Audio Coding (AAC) and MPEG-4 variants, including m4p, a proprietary version of AAC in MP4 format with Apple-developed digital rights management.

Compressed Video Files
AVCHD (Advanced Video Codec High Definition): A high-end consumer format developed by Panasonic and Sony for HD systems; uses MPEG-4 H.264 encoding.

AVI (Audio Video Interleave): Interface format developed by Microsoft and compatible with RIFF; contains multiple streams to accommodate different data types, including control of separate AV material; format creates compressed files that are moderately large, but that retain high image and sound quality.

DivX: An open-source video-compression software scheme jointly developed by DivX Networks, intended primarily for program distribution, rather than postproduction.

FLV (Flash Video Format): Developed by Adobe and used for Internet delivery of data-compressed media files.

H.26L Series:
A series of flexible AV codecs developed by Video Coding Experts Group (VCEG) and MPEG and used as a capture format for digital cameras and editing workstations; designed as two distinct layers—a video coding layer (VCL) and a network adaptation layer (NAL) responsible for packaging the coded data based on the specific characteristics of the network or data channel being used; one of the codec standards for Blu-ray discs and widely used for Internet streaming and cable broadcast, satellite TV services and videoconferencing; often referred to as AVC and MPEG-4 part 10.

MOV: A proprietary QuickTime format developed by Apple for encoding digital video, digital audio and images; supported by Apple's Final Cut Studio and Logic Studio, and licensed to many other vendors for image-capture and AV editing; a plug-in architecture supports additional third-party codecs.

MPEG: A digital-video format standardized by the Moving Picture Experts Group, incorporating both MPEG-1 and MPEG-2 audio/video compression at various image sizes and compression schemes; includes MPEG-4/MP4 format (.mp4 extension) used both for storage and online delivery of audio and visual media with low bit-rate encoding schemes and support of digital rights management; separate data compression for multichannel audio and video material (video with MPEG-4 video encoding and audio using AAC compression; replayed with Apple QuickTime Player).

WMV (Windows Media Video): Format developed by Microsoft for Internet streaming and data storage.

Mel Lambert has been intimately involved with AV production industries on both sides of the Atlantic for more years than he cares to remember. He's now principal of Content Creators, a Los Angeles-based editorial and photographic service. You can reach him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

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