Performance analysis of AAC audio codec and comparison of Dirac Video Codec with AVS-china. Under guidance of Dr.K.R.Rao Submitted By, ASHWINI S URS

Transcription

1 Performance analysis of AAC audio codec and comparison of Dirac Video Codec with AVS-china Under guidance of Dr.K.R.Rao Submitted By, ASHWINI S URS

2 Outline Overview of Dirac Overview of AVS-china Overview of AAC Performance of Dirac codec Performance of AAC codec References

3 Overview of Dirac Dirac[1] is a hybrid video codec developed by British Broadcasting Corporation (BBC). Dirac is a hybrid video codec because it involves both transform and motion compensation. The key feature of Dirac is that it is an open technology, which means that the technology can be used without payment of licensing fees. Dirac uses modern techniques like, wavelet transform and arithmetic coding for entropy coding. The applications of Dirac range from high definition television (HDTV) to web streaming due to its flexibility.

4 Fig.1 Block Diagram of Dirac Encoder [1]

5 Overview of AVS-China Audio-video coding standard (AVS) is a working group of audio and video coding standard in China, which was established in Based on versatile applications in the area of video, AVS-china is categorized into various profiles[16]. AVS-china consists of four profiles namely: Jizhun (base) profile, Jiben (basic) profile, Shenzhan (extended) profile and Jiaqiang (enhanced) profile, defined in AVS-video targeting to different applications (Table.1) [16]. AVS- china has different parts for various categories. AVS Part- 2 defines Jizhun profile. Jizhun profile is preferable for high coding efficiency on video sequences of higher resolutions, at the expense of moderate computational complexity.

6 Profiles Key applications Jizhun profile Jiben profile Television broadcasting, HDTV, etc. Mobility applications, etc. Shenzhan profile Video surveillance, etc. Jiaqiang profile Multimedia entertainment, etc. Table.1 Application based profiles of AVS [16]

7 Part Category 1 System 2 Video 3 Audio 4 Conformance test 5 Reference Software 6 Digital media rights management 7 Mobile video 8 Transmit AVS via IP network 9 AVS file format 10 Mobile speech and audio coding Table.2 Different Parts of AVS-china

8 Fig.3 Typical AVS-China video coding Chain [16]

9 Fig.4 Block diagram of AVS-china encoder [15]

10 Overview of AAC AAC [2] consists of three profiles, namely: main profile, low-complexity profile and scalable sampling rate (SSR) profile. The key feature of low-complexity profile is, it deletes the prediction tool and reduces the temporal noise shaping tool in complexity. Supports Sample frequencies from 8 khz to 96 khz (official MP3: 16 khz to 48 khz) [4]. Superior performance at bit rates > 64 kbps and at bit rates reaching as low as 16 kbps. Improved compression provides higher-quality audio with smaller bit rates. AAC can accommodate two basic bit stream formats: Audio data interchange format (ADIF) and Audio data transport stream (ADTS) [10].

11 Fig.5 Block Diagram AAC Encoder [7]

12 Performance analysis of dirac video codec QCIF sequence: Akiyo Total No: of frames : 300 frames. Width : 176. Height: 144. Frame rate: 30fps. QF Original File Size (KB) Compressed File Size (KB) Compression Ratio Y-MSE Y-PSNR Y- SSIM : : : : : : : : : : : Lossless : Table.3 Performance of Dirac for Akiyo test sequence (150 frames)

13 CIF sequence: Tempete Total No: of frames : 260 frames. Width : 352. Height: 288. Frame rate: 30fps QF Original File Size (KB) Compressed File Size (KB) Compression Ratio Y-MSE Y-PSNR Y- SSIM : : : : : : : : : : : Lossless : Table.4 Performance of Dirac for Tempete test sequence (90 frames)

14 Original Sequence Recon image QF=0 Recon image QF=10 Recon image lossless mode

15 Original sequence Recon sequence for QF= 0 Recon sequence for QF=10 Recon sequence lossless mode

16 Performance analysis of the AAC codec: Results: Length of audio sequence = 2.13 minutes. Bitrate for encoded sequence = (2.01*8)/(2.13*60) = 0.126Mbps Bitrate for the decoded sequence = (24.4*8)/(2.13*60) = 1.528Mbps File format No: of Frames in a sequence Encoding time(seconds) Decoding time(seconds) Original Size(MB) Compressed Size(MB) Compression Ratio ADTS :1

17

18

19 Acronyms AAC Advanced audio coding. ADIF Audio data interchange format. ADTS Audio data transport stream. AES Audio engineering society. AFC Adaptation field control. AVC Advanced video coding. AVS Audio video coding standard. BBC British broadcasting corporation. CIF Common intermediate format. HDTV High definition television. ISDB-T Integrated services digital broadcasting Terrestrial. MPEG Moving picture experts group. MSE Mean square error. M/S Mid/Side. PSNR Peak signal to noise ratio. QCIF Quarter common intermediate format SSIM Structural similarity index measurement. SSR Scalable sampling rate. TNS Temporal noise shaping.

20 References [1] T. Borer, and T. Davies, Dirac video compression using open technology, BBC EBU Technical Review, July [2] MPEG 2 Advanced audio coding, AAC. International Standard IS , ISO/IEC JTC1/SC29 WG11, [3] MPEG. Information technology - Generic coding of moving pictures and associated audio information, part 4: Conformance testing. International Standard IS , ISO/IEC JTC1/SC29 WG11, [4] M. Bosi and M. Goldberg Introduction to digital audio coding and standards, Boston: Kluwer academic publishers, c2003. [5] A. Puri, X. Chen and A. Luthra, Video coding using the H.264/MPEG-4 AVC compression standard, Signal processing: image communication, vol. 19, issue 9, pp , Oct [6] K. Brandenburg, MP3 and AAC Explained, AES 17th International conference, Florence, Italy, Sep [7] P.A. Sarginson, MPEG-2: Overview of systems layer, BBC RD 1996/2. [8] Dirac software download and source code: [9] AVS-china software download: ftp:// /public/avs_doc/avs_software [10] H. Murugan, M.S.E.E Thesis, University of Texas at Arlington, TX Multiplexing H264 video bit-stream with AAC audio bit-stream, demultiplexing and achieving lip sync during playback, May [11] AVS-China official website: [12] M. Uehara, Application of MPEG-2 systems to terrestrial ISDB (ISDB-T), Proceedings of the IEEE, vol.94, pp , Jan

21 References [13] MSU Video Quality measurement tool: [14] A. Ravi and K.R. Rao, Performance analysis and comparison of the Dirac video codec with H.264/ MPEG-4 Part 10 AVC", Submitted to Journal of VCIR, Sept [15] L.Fan, Mobile Multimedia Broadcasting Standards, ISBN: , Springer US, [16] Lu Yu, Sijia Chen, Jianpeng Wang, Overview of AVS-video coding standards, special issue on AVS, SPIC, vol. 24, pp , April [17] Dirac video codec - A programmer's guide: [18] Digital audio compression standard (AC-3, E-AC-3), revision B, ATSC Document A/52B, Advanced Television Systems Committee, Washington, D.C., Jun. 14, [19] Video test sequences QCIF and CIF sequences: [20] Z. Wang, et al Image quality assessment: From error visibility to structural similarity, IEEE Trans. on Image Processing, vol. 13, pp , Apr [21] L.Yu et al., Overview of AVS-Video: Tools, performance and complexity, SPIE VCIP, vol. 5960, pp ~ , Beijing, China, July [22] C. C. Todd, et.al, AC-3: perceptual coding for audio transmission and storage, presented at the 96th Conv. Audio Engineering Soc., 1994, Preprint [23] Power point slides by L.Yu, chair of AVS video :