MPEG4 Conformance Testing For Digital Video Archiving Max Gustashaw University of North Carolina-Chapel Hill Tyler Johnson University of North Carolina-Chapel Hill

Folkstreams  Folkstreams.net is a national preserve of documentary films about American folk or roots culture. Produced by independent filmmakers, these hard-to- find films give voice to the arts and experience of diverse American groups.  Folkstreams.net also encourages alternative forms of filmmaking about subjects neglected by mainstream corporate media.

Folkstreams - streaming  Folkstreams.net makes these films easy to find and to see by video-streaming them on the Internet, and also provides in-depth and reliable contextual materials about the subjects and the filmmaking.  They are streamed on the website together with background materials that highlight the history and aesthetic importance of the traditions and the films.

Formats Employed  16mm film original Digital Betacam  Real  QuickTime  ASF  MPEG4

General Goal For Digital Video Archiving  Ensure that original is preserved You can always go back to the original to make new distribution copies, right?  Ensure that distribution (compressed) copies are preserved These are how the public accesses the data  Anticipate that compressed formats will in many cases be the originals.  Make sure that compressed video files are playable in years Will the vendor be in business? Will the player even run? Are open source decoders available?

Project Goal  To determine which CODECs produce media files that are adhere to MPEG’s qualifications for the MPEG4 standard, and, by isolating the factors that affect these results, to highlight issues that may influence the strength of archival and distribution plans.

MPEG4 Goal  MPEG4 identified as a key format for compressed media  Experience has shown commercial MPEG4 files are not inter-operable  Test commercial encoders to see their level of standard compliance  Learn more about the standard in order to better be able to advise the university as to archiving strategies for compressed media

Method  Encode two test files using the target codec  Analyze each resultant file using Mindego 4500 MPEG4 Analyzer  Log errors

Clips  Born for Hard Luck  Cowboy Poets Could not embed MPEG4 clips in this presentation because PowerPoint will not recognize our MPEG4 files.

Codecs Used  3ivx (3ivx)  Compression Master (Popwire)  Libavcodec MPEG4 (FFMPEG)  MSMPEG4v2 (????????)  QuickTime (Apple)  Sorenson Squeeze (Sorenson Media)  DivX (DivXNetworks )  4Coder (envivio)

Mindego 4500 Analyzer  Deconstructs bit streams  Tests for MPEG4 conformance- the standard  Tests for conformance to industry profiles Currently supports ISMA  Visual / macroblock analysis  H.264 support planned  Educational pricing available  Mindego Analyzer demo

Results  Comments  Minor errors  Major errors * All codecs produced errors !

3ivx  Born for Hard Luck Visual session size (320,240) does not comply with "Typical Visual Session Size" (176,144) for Simple Profile Level Group of VOP or VOP start code not found  Cowboy Poets Visual session size (320,240) does not comply with "Typical Visual Session Size" (176,144) for Simple Profile Level Group of VOP or VOP start code not found Visual start code not found in the next byte aligned position.

Compression Master  BHFL Full analysis failed to run Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Simple Profile Level Visual start code not found in the next byte aligned position.  CP Full analysis failed to run Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Simple Profile Level 2 Demo encoder limited to 20 seconds

Libavcodec MPEG4 (FFMPEG)  BFHL Visual session size (320,240) does not comply with "Typical Visual Session Size" (176,144) for Simple Profile Level Visual start code not found in the next byte aligned position.  CP Visual session size (320,240) does not comply with "Typical Visual Session Size" (176,144) for Simple Profile Level Visual start code not found in the next byte aligned position.

MSMPEG4v2  BFHL Analyzer will not load file ‘Unknown stream type’  CP Analyzer will not load file ‘Unknown stream type’

QuickTime  BFHL Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Advanced Simple Profile Level Max video packet length found to be bits that exceeded the bound of 4096 bits for Advanced Simple Profile Level Visual start code not found in the next byte aligned position.  CP Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Advanced Simple Profile Level Max video packet length found to be bits that exceeded the bound of 4096 bits for Advanced Simple Profile Level Visual start code not found in the next byte aligned position.

Sorenson Squeeze  BFHL Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Simple Profile Level Visual start code not found in the next byte aligned position.  CP Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Simple Profile Level Visual start code not found in the next byte aligned position.

DivX  BFHL Analyzer will not load file ‘Unknown stream type’  CP Reserved value used for coding VOL priority Visual start code not found in the next byte aligned position Reserved value used for coding Video Object Type indication Reserved value used for coding chroma format Non-Rectangular Video not supported in the current version Reserved value used for coding VOL version ID The marker bit after video object layer shape found to be zero The marker bit after vop_time_increment_resolution found to be zero The marker bit found to be zero after vol_width Marker bit found to be zero after vop_time_increment base Coded Value of vop_time_increment exceeds the value of vop_time_increment_resolution Visual start code not found in the next byte aligned position The marker bit after latter_half_bitrate found to be zero Visual Object Start code not found FGS not supported in this version For MB No:22: Code not found in VLC table for cbpy The marker bit after fixed vop time incrementis not equal to Forbidden value '0' found for vop_fcode_forward For MB No63: Code not found in VLC table for mb_type For MB No:186, Block No:0: Code not found in VLC table for inter block

envivio 4coder  BFHL Visual session size (320,240) does not comply with "Typical Visual Session Size" (352,288) for Simple Profile Level Visual start code not found in the next byte aligned position  CP Reserved value used for VOL version ID Visual start code not found in the next byte aligned position Start code found from the next byte aligned position when reading from macroblock

Conclusions  MPEG4 is complicated  Wary of industry alliances  H.264 likely to be adopted widely because of VC and broadcast efficiency  MPEG4 arbitrary shape and fancy encodings dependent on market demand  Analyzer is a critical tool – can’t rely on interop  Market competition goals can conflict with archival needs Commercial applications Purposefully non-standard to dominate the market

Next Steps  More comprehensive tests  Need alternate conformance tool to verify results  Make an archive plan MPEG4 Visual (part 2) has many profiles that must be specified / evaluated MPEG4 part 10 (H.264) has many profiles that must be specified / evaluated  Get smarter, get wise