1. Perceived Audiovisual Quality of Low-Bitrate Multimedia Content Stefan Winkler, Christof Faller IEEE Transactions on Multimedia vol. 8, no. 5, pp. 973-980, Oct. 2006 http://stefan.winkler.net/publications.html

2. Test Overview Mobile video Low bitrates, small-size clips 6 AV source clips (QCIF, ~8s each) NameVideoAudio BuildingsSlow pan across city skylineOrchestral background music ConversationCamera switching between woman and man (head-and-shoulders) Male and female voice FootballAmerican football (VQEG)Crowd cheering and chanting, female commentator Music videoMusic video clipRock music with vocals Trailer 1Action movie trailer; scene cuts, high motion Theme music, voice-over Trailer 2Romance movie trailer with credits; scene cuts Theme music, voice-over

3. Test Setup H.264 encoder Video decoder AV source sequence Codec, bitrate, frame rate AAC-LC encoder Audio decoder AV test sequence Bitrate, channels, sampling rate Audio Video Video: H.264, H.263, MPEG-4 codecs Frame rates: 8 fps, 15 fps Audio: Mono/stereo Sampling rates: 8–32 kHz

4. Test Conditions TotalVideoAudio 40 kb/s24 kb/s16 kb/s 40 kb/s32 kb/s 8 kb/s 56 kb/s24 kb/s32 kb/s 56 kb/s32 kb/s24 kb/s 56 kb/s40 kb/s16 kb/s 56 kb/s48 kb/s 8 kb/s 72 kb/s40 kb/s32 kb/s 72 kb/s48 kb/s24 kb/s CodecFrame rateBitrate H.2648 fps24 kb/s H.2648 fps32 kb/s H.2648 fps40 kb/s H.2648 fps48 kb/s H.2638 fps48 kb/s MPEG-48 fps48 kb/s H.26415 fps24 kb/s H.26415 fps32 kb/s H.26415 fps40 kb/s H.26415 fps48 kb/s ChannelsSamplingBitrate mono 8 kHz 8 kb/s mono16 kHz16 kb/s mono22 kHz24 kb/s mono32 kHz32 kb/s mono22 kHz32 kb/s stereo22 kHz32 kb/s stereo16 kHz32 kb/s Video Audio Audiovisual

5. Subjective Assessment 17” LCD screen Comfortable viewing distance Sound-proof room Studio headphones 30 min. test session, in 3 parts with breaks 24 non-expert viewers

6. Method: Absolute Category Rating (ACR) Viewers rate quality on discrete scale (0-10) 3-part test session Subjective Assessment Test sequence Vote

7. Subjective Data