Programs for our deep learning based complexity reduction approach for HEVC, at both intra- and inter-modes.

Deep Learning Based HM Encoder (Test at Intra-mode)

Relative folder: HM-16.5_Test_AI/

This encoder is used for evaluating the performance of our deep ETH-CNN based approach [1] (improved from the conference version [2] published on IEEE ICME) at All-Intra configuration. The main part is modified from the standard reference software HM 16.5 [3], coded with C++. The proposed ETH-CNN is realized based on Tensorflow, coded with Python 3.5. For evaluating the performance of our deep learning based approach, the Python program is invoked inside the HM encoder. To encode a YUV file, the probability of CU partition for all the frames is predicted in advance, before the encoding process in HM really starts. Compared with the upper and lower thresholds at three levels, the probability is read to finally determine the CU partition by HM. In this way, most redundant checking of RD cost checking can be skipped, thus save the overall encoding time significantly.

Process

1. Before encoding the first frame, HM invokes the Python program video_to_cu_depth.py via a command line with some essential paramaters, containing YUV file name, frame width, frame height and QP.

2. The Python program reads the YUV file and other essential parameters, to predict the probability of CU partition for all the frames and save it in file cu_depth.dat.

3. HM encodes all the frames according to the predicted CU partition probability from cu_depth.dat, thus simplifying the RDO process by skipping redundant checking of RD cost.

Source

In HM 16.5, four C++ files have been modified, as below.

• source/App/TAppEncoder/TAppEncCfg.cpp

• source/Lib/TLibCommon/TComPic.h

• source/Lib/TLibEncoder/TEncGOP.cpp

• source/Lib/TLibEncoder/TEncCu.cpp

Among them, TAppEncCfg.cpp directly invokes the Python program.

Note: it is assumed that the default Python is Python 3 in the system (Windows or Linux). If Python 3 is not default, please edit the 2319th line of TAppEncCfg.cpp by changing the string python into python3, and rebuild the HM.

Also, two Python files are included for predicting the CU partition with the proposed deep networks. The top file is video_to_cu_depth.py, monitoring the overall procedure of adopting ETH-CNN, together with necessary steps such as file reading/writting, data transferring, network feeding, etc. The specific network architecture is defined in net_CNN.py.

For more details, please refer to the comments in these source codes.

This program is used to evaluate the performance of our deep ETH-CNN based approach at All-Intra configuration.

Running Instructions

1. Install Tensorflow. Versions $\ge$ 1.8.0 are recommanded.

2. Path into HM-16.5_Test_AI/Release

   Set upper/lower thresholds for 3-level CU partition in file Thr_info.txt

   Format: [$\bar{\alpha}_1$ $\alpha_1$ $\bar{\alpha}_2$ $\alpha_2$ $\bar{\alpha}_3$ $\alpha_3$]

   Example: [0.5 0.5 0.5 0.5 0.5 0.5]

3. Run TAppEncoderStatic on Linux or TAppEncoder.exe on Windows.

   Examples: RUN_AI.sh and RUN_AI.bat

Note: It is highly recommended to run on Linux (64-bit) platform, which supports encoding high-resolution video sequences normally. If to run with other platform, you need to rebuild the project and re-generate the executable files. Also, please make sure the path of YUV file is not so long (shorter than 900 characters), because the file path is a part of a command line for invoking the Python program and the maximum length of the command line is 1000.

Deep Learning Based HM Encoder (Test at Inter-mode)

Relative folder: HM-16.5_Test_LDP/

This encoder is used for evaluating the performance of our deep ETH-CNN + ETH-LSTM based approach [1] at Low-Delay-P configuration. The main part is modified from the standard reference software HM 16.5, coded with C++. The proposed ETH-CNN and ETH-LSTM are realized based on Tensorflow, coded with Python 3.5. For evaluating the performance of our deep learning based approach, the HM and the Python program are linked together via sharing intermediate information when running both the programs. When encoding a YUV file, the CU partition is predicted frame-wise in accord with the encoding process in HM. For a certain frame, a simplified setting is adopted for quick pre-encoding, to obtaining the residue of this frame in HM. Next, the residue is fed into ETH-CNN + ETH-LSTM in the Python program. Then the Python program predicts the probability of CU partition for this frame. Compared with the upper and lower thresholds at three levels, the probability is read to finally determine the CU partition by HM. In this way, most redundant checking of RD cost can be skipped, thus save the overall encoding time significantly.

Process

1. During encoding one frame, HM adopts a simplified setting (CU size and PU size are all the maximum, 64$\times$64, except on the right/bottom edge without full-size CTUs) to quickly pre-encode the frame, for obtaining the residue. Then the residue frame is saved into file resi.yuv. Note that the quick pre-encoding for residue is not included in the standard HM. Instead, it is introduced by our approach, to provide the input for ETH-CNN at inter-mode.

2. In HM, some essential parameters are wirtten into file command.dat.

   Format: Frame_index Frame_width Frame_height QP [end]

   Example: 19 416 240 22 [end]

3. HM generates a signal file pred_start.sig, indicating the residue file and command file are ready and the Python program can start to run. Here the Python program need only check whether the siginal file exists rather than the content. So the siginal file can be null, for simplicity.

4. Once pred_start.sig is detected by the Python program, some essential files are read, containing the residue resi.yuv, the command command.dat and the previous state of ETH-LSTM state.dat (if have).

5. The residue frame and the LSTM state are fed into ETH-CNN + ETH-LSTM. Then ETH-LSTM runs ahead for one time step, and the file state.dat is updated. Also, the predicted CU partition probability for the whole frame, is saved in file cu_depth.dat.

6. After updating the state and generating cu_depth.dat, the Python program generates an end signal pred_end.sig, indicating the prediction for current frame is finished.

7. Once pred_end.sig is detected by HM, the probability of all possible CUs are read from cu_depth.dat, based on which the CU partition is determined.

8. HM encodes the current frame according to the predicted CU partition, thus simplifying the RDO process by skipping redundant checking of RD cost.

Source

In HM 16.5, five C++ files have been modified, as below.

• source/Lib/TLibCommon/TComPic.h

• source/Lib/TLibEncoder/TEncGOP.cpp

• source/Lib/TLibEncoder/TEncCu.cpp

• source/Lib/TLibEncoder/TEncSearch.cpp

• source/Lib/TLibEncoder/TEncSlice.cpp

Among them, the TEncGOP.cpp directly invokes ETH-CNN + ETH_LSTM.

Also, three Python files are included for predicting the CU partition with the proposed deep networks. The top file is resi_to_cu_depth_LDP.py, monitoring the overall procedure of adopting ETH-CNN + ETH-LSTM, together with necessary steps such as file reading/writting, data transferring, network feeding, etc. The specific network architecture is defined in net_CNN_LSTM_one_step.py, and some constants are stored in config.py.

For more details, please refer to the comments in these source codes.

This program is used to evaluate the performance of our deep ETH-CNN+ETH-LSTM based approach at the Low-Delay-P configuration.

Running Instructions

1. Install Tensorflow. Versions $\ge$ 1.8.0 are recommanded.

2. Path into HM-16.5_Test_LDP/Release

3. Set upper/lower thresholds for 3-level CU partition in file Thr_info.txt

   Format: [$\bar{\alpha}_1$ $\alpha_1$ $\bar{\alpha}_2$ $\alpha_2$ $\bar{\alpha}_3$ $\alpha_3$]

   Example: [0.4 0.6 0.3 0.7 0.2 0.8]

4. Ensure there exists no any signal file, pred_start.sig or pred_end.sig, for avoiding unproper behavier of communication between the HM encoder and the python program resi_to_cu_depth_LDP.py.

5. Run resi_to_cu_depth_LDP.py with Python 3.5, and Initializing. Please wait... is shown.

6. Wait for about 1~10s, until Python: Tensorflow initialized. is shown.

7. Run TAppEncoderStatic on Linux or TAppEncoder.exe on Windows.

   Examples: RUN_LDP.sh and RUN_LDP.bat

Note: It is highly recommended to run on Linux (64-bit) platform, which supports encoding high-resolution video sequences normally. If to run with other platform, you need to rebuild the project and re-generate the executable files.

Training at Intra-mode

Relative folders: HM-16.5_Extract_Data/, AI_Info/, Extract_Data/ and ETH-CNN_Training_AI/

These programs are used for training the deep ETH-CNN at All-Intra configuration. Require: 12 YUV files (and 96 Info_XX.dat files, optional)

1. Build databases: Compress 12 YUV files with encoder HM-16.5_Extract_Data/bin/TAppEncoderStatic at 4 QPs, to extract str_XX.bin, Info_XX.dat and log_XX.txt files.

   (This step can be skipped, because all Info_XX.dat files are already provided in folder AI_Info/ )

2. Extract data:

   To configure: variables YUV_PATH_ORI and INFO_PATH in Extract_Data/extract_data_AI.py.

   Run Extract_Data/extract_data_AI.py to get training, validation and test data. Each data file is shuffled during the program's running. Sample size: 4992 bytes.

3. Train:

   Run ETH-CNN_Training_AI/train_CNN_CTU64.py following the instruction ETH-CNN_Training_AI/readme.txt.

Training at Inter-mode

Relative folders: HM-16.5_Extract_Data/, HM-16.5_Resi_Pre/, LDP_Info/, Extract_Data/, ETH-CNN_Training_LDP/ and ETH-LSTM_Training_LDP/

These programs are used for training the deep ETH-CNN and ETH-LSTM at Low-Delay-P configuration.

Require: 111 YUV files (and 888 Info_XX.dat files, optional)

1. Build databases: (1) Compress 111 YUV files with encoder HM-16.5_Extract_Data/bin/TAppEncoderStatic at 4 QPs, to extract str_XX.bin, Info_XX.dat and log_XX.txt files.

   (This step can be skipped, because all Info_XX.dat files are already provided in folder LDP_Info/ )

   (2) Compress 111 YUV files with encoder HM-16.5_Resi_Pre/bin/TAppEncoderStatic at 4 QPs, to obtain 444 resi_XX.yuv files.

2. Extract data for ETH-CNN:

   To configure: variables CONFIG, YUV_PATH_RESI and INFO_PATH in Extract_Data/extract_data_LDP_LDB_RA.py.

   Run Extract_Data/extract_data_LDP_LDB_RA.py to get training, validation and test data. For each data file, both shuffled and unshuffled versions are generated. Sample size: 16516 bytes.

3. Train ETH-CNN: Run ETH-CNN_Training_LDP/train_resi_CNN_CTU64.py for all 4 QPs at one time.

4. Extract data for ETH-LSTM:

   To configure: variables MODEL_FILE, INPUT_PATH and OUTPUT_PATH in ETH-LSTM_Training_LDP/get_LSTM_input.py.

   Run ETH-LSTM_Training_LDP/get_LSTM_input.py. Use unshuffled training/validation/test files in step 2 to generate data for ETH-LSTM. Sample size: 37264 bytes.

5. Train ETH-LSTM:

   Run ETH-CNN_Training_LDP/train_LSTM_CTU64.py for 4 QPs separately.

References

[1] M. Xu, T. Li, Z. Wang, X. Deng, R. Yang and Z. Guan, "Reducing Complexity of HEVC: A Deep Learning Approach", in IEEE Transactions on Image Processing (TIP), vol. 27, no. 10, pp. 5044-5059, Oct. 2018.

[2] T. Li, M. Xu and X. Deng, "A deep convolutional neural network approach for complexity reduction on intra-mode HEVC," 2017 IEEE International Conference on Multimedia and Expo (ICME), Hong Kong, Hong Kong, 2017, pp. 1255-1260.

[3] JCT-VC, “HM Software,” [Online]. Available: https://hevc.hhi.fraunhofer.de/svn/svn_HEVCSoftware/tags/HM-16.5/, 2014, [Accessed 5-Nov.-2016].