Multimedia

Types of compression

• Uncompressed
• Lossless compressed
• Lossy compressed

Codecs

• Portmanteau word for Coder+Decoder
• Software which encodes and decodes audio/video
• Coder: encodes for transmission and storage
• Decoder: decodes for playback and editing
• Example:
  • Audio
    • mp3 (Lossy compressed)
  • Video
    • H.264 (Lossless compressed)

Container (Video+Audio) Formats

• Refer: https://developer.mozilla.org/en-US/docs/Web/Media/Formats/Containers
• WebM (Web Media)
  • royalty free and open source from Google
  • based on Matroska container format
  • Video Codec: VP8 or VP9
  • Audio Codec: Vorbis or Opus
• MP4 (Moving Picture Experts Group 4)
  • aka MPEG-4
  • Video Codecs: AVC (H.264), AV1, VP9 etc.
  • Audio Codecs: AAC, FLAC, Opus etc.
• MKV (Matroska Video files)
  • open format
  • Video Codecs: H.264, H.265, VP9, AV1 etc.
  • Audio Codecs: MP3, AAC, AC3, DTS, FLAC etc.
• MOV (Apple QuickTime Movie)
  • aka QTFF, QT
  • Video Codecs: AVC (H.264), Cinepak, DV etc.
  • Audio Codecs: AAC, Apple Lossless (ALAC), HE-AAC etc.
• OGG
  • free and open format from Xiph.org
  • Video Codecs: Theora, VP8, VP9 etc.
  • Audio Codecs: FLAC, Opus, Vorbis etc.
• 3GP (Third Generation Partnership)
• AVI (Audio Video Interleave)

Audio Formats

• WAV (Waveform Audio File Format)
  • aka WAVE
  • container format
  • Audio Codecs: ADPCM, MPEG-1, µ-Law etc.
• FLAC (Free Lossless Audio Codec)
  • lossless codec
  • container: FLAC
• MP3
  • lossy compression codec
  • containers: MP4
• AAC
  • patented
  • lossy compression codec
  • containers: MP4, 3GP

Choosing Format

• Audio only:
  • Compressed/general purpose: MP3
  • Losslessly compressed: FLAC/ALAC
  • Uncompressed: WAV
• Video+Audio:
  • General purpose and open format: WebM
  • General purpose: MP4
  • High compression for slow connection: 3GP