PASIG Digital Preservation BOOTcamp Best* Practices in Preserving Common Content Types: AudioVisual files

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1 PASIG Digital Preservation BOOTcamp Best* Practices in Preserving Common Content Types: AudioVisual files Kara Van Malssen AudioVisual Preservation Solutions MAY 22, 2013

2 File 1 File 2 File 3 Format PDF 1.2 PDF 1.2 PDF 1.4 File 1 File 2 File 3 Format PDF 1.2 PDF 1.2 PDF 1.4 Page Count Encryption Yes No Yes File Size 1 MB 120 MB 2 MB Valid No Yes No Well-formed Yes Yes Yes

3 File 1 File 2 File 3 Format.mov.mov.mp4

4 Containers and Encoded Essence

5 Container Essence

6 Container Essence

7 Types of possible Data Within AV Containers Video Audio Text Metadata Image Captions Subtitles Chapters Attachments Timecode Matroska Container Specifica1on

8 formats{ common video File Container QuickTime (.mov) DV (.dv) MPEG-4 (.mp4) MPEG-2 (.mpg) AVI (.avi) MXF (.mxf) Matroska (.mkv) Flash Video (.flv)

9 formats{ COmmon video stream encoding MPEG-2 MPEG-4 (H.264, AVCHD, etc) DV ProRes JPEG2000 FFV1 Theora Sorenson Uncompressed*

10 Formats{ common audio File Container WAV (.wav) BWF (.wav) MP3 (.mp3) MP2 (.mp2) AIFF (.aiff) FLAC (.flac)

11 formats{ COmmon audio stream encodings PCM MP3 AAC Windows Media Audio AC3 FLAC

12 ffmpeg -codecs Codec encoder/decoder A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "coder-decoder" or, less commonly, "compressordecompressor". -

13 A Primer on Codecs for Moving Image and Sound Archives Chris Lacinak

14 More info on AV file formats/stream encodings:

15 Significant properties/ characteristics?

16 Some additional important AV file characteristics... General Video audio data rate duration file size *other embedded data color space sampling rate aspect ratio bit depth frame size channels frame rate bit depth pixel format chroma subsampling

17 MPEG-4 Encoding Data rate = 3500 Kbps

18 MPEG-4 Encoding Data rate = 1000 Kbps

19 MPEG-4 Encoding Data rate = 250 Kbps

20 Data Rate & File Size VIDEO 1 hour 210 Mb/s 92 GB VIDEO 1 hour 50 Mb/s 22 GB VIDEO 1 hour 25 Mb/s 11 GB VIDEO 1 hour 1.5 Mb/s 1 GB AUDIO 1 hour 4.6 Mb/s 2 GB AUDIO 1 hour 128 Kb/s 56 MB

21 Data Rate, File Size & Usage VIDEO 1 hour 210 Mb/s 92 GB Preserva1on Master VIDEO 1 hour 50 Mb/s 22 GB Preserva1on Master or Mezzanine VIDEO 1 hour 25 Mb/s 11 GB Preserva1on Master or Mezzanine VIDEO 1 hour 1.5 Mb/s 1 GB Access Copy AUDIO 1 hour 4.6 Mb/s 2 GB Preserva1on Master AUDIO 1 hour 128 Kb/s 56 MB Access Copy

22 Digital AV File Types for Archival Purposes Preservation Master = highest possible data rate, open and interoperable encoding, appropriate container format Mezzanine (access / edit master) = medium data rate, open and interoperable encoding, appropriate container format Proxy (access copy) = low data rate, any encoding, any container

23 mediainfo [filename] ffmpeg -f lavfi -i mandelbrot -t 10 -c:v v210 v210.avi command-spiration: ffmpeg4archivists, Dave Rice & Misty De Meo, AMIA 2012

24 mediainfo [filename]

25 ffprobe -show_format -show_streams -show_data -show_error -show_versions [filename]

26 exiftool [filename]

27 Preservation format?

28 AUDIO reformatting = linear PCM / BWF (WAV) ~ min 24 bit / 48 KHz IASA, EBU, US-FADGI

29 ANALOG MIGRATION (grossly oversimplified) composite or s-video component Uncompressed DV Pro Res... Uncompressed DV MPEG- 2 Uncompressed DV DNx

30 DIGITAL MIGRATION (fairly oversimplified) firewire DV

31 H.264

32 DV XDCam HD MPEG2

34 But what format should I use? Budget? Infrastructure? Access requirements? Scale? Mission & Goals? Sustainability?

35 ...It depends if there was a standard or best practice, I would point you to it

36 1. Know your files well 2. Understand your options Recommendations 3. Make informed decisions 4. Test before you transcode 5. Sustainability criteria is important!

The Perils of Preserving Digitized and Born-Digital Video

The Perils of Preserving Digitized and Born-Digital Video A Presentation for the Council of Intermountain Archivists Fall, 2011 Jimi Jones Digital Audiovisual Formats Specialist Office of Strategic Initiatives