Emc Corporation

Daniel Gardere

Sorin Faibish

Wayne William Duso

Peter C Bixby

John Forecast

Michel Noury

Seyfullah H Oguz

Sebastian Keller

Jie Wang

Sebastien Keller

Jean Louis Rochette

Metadata for splicing of an encoded digital motion video stream (such as an MPEG Transport Stream) is prepared in real time while recording at the encoding bit rate and faster than encoded bit rate for off line encoding independent of the bit rate and mechanisms for ingestion of the data stream into data storage. Preprocessing is performed during a metered file transfer protocol (FTP) and includes pseudo real-time encoding. The preprocessing includes Group of Pictures (GOP) level pre-processing of splicing In Points and results in an intimate linkage between metadata and the file system in which the video data is stored. The preferred file system enables access to metadata in parallel to writing the data on disk. The pre-processing is performed simultaneous to writing the data to the disk using a carousel type buffer mechanism.

Preparation of metadata for splicing of encoded MPEG video and audio

To produce a paused MPEG coded video stream from an original MPEG coded video stream, an I frame is extracted from the original stream, and a Group of Pictures for a 'pause' (a pause GOP) is constructed containing the extracted I frame, some 'frozen' frames, and padding. Each &#x201c;frozen&#x201d; frame is a P frame that repeats the I frame. When a pause is requested in the original stream, a seamless transition is made from the I frame to the pause GOP, and the pause GOP is played in a loop until a resume is requested. To resume, the pause GOP is completed and a seamless transition is made to continue in the original stream from the I frame where the pause had begun.

Method of pausing an MPEG coded video stream

MPEG coded video data includes groups of pictures (GOPs). Each group of pictures includes one or more I-frames and a plurality of B- or P-frames. To produce an MPEG slow-forward coded video stream, the coding type of each frame in the MPEG coded video data is identified, and freeze frames are inserted as a predefined function of the identified coding type and as a predefined function of a desired slow down factor. In a preferred implementation, for a slow-down factor of n, for each original I- or P-frame, (n&#x2212;1) backward-predicted freeze frames are inserted, and for each original B-frame, (n&#x2212;1) copies of the original B-frames are added, and a selected amount of padding is added to each copy of each original B-frame in order to obtain a normal play bit rate and avoid video buffer overflow or underflow.

Generation of MPEG slow motion playout

Original-quality MPEG coded video is processed to produce reduced-quality MPEG coded video for trick mode operation by removing non-zero AC DCT coefficients from the 8&#xd7;8 blocks of I-frames of the MPEG coded video to produce I-frames of reduced-quality MPEG coded video, and inserting freeze frames in the reduced-quality MPEG coded video. Preferably, the coded video is stored in a main file, a fast-forward file and a fast-reverse file. The fast forward file and the fast reverse files contain reduced-quality I frames corresponding to original-quality I frames in the main file. A reading of the main file produces an MPEG transport stream for an audio-visual presentation at a normal rate, a reading of the fast-forward file produces an MPEG transport stream of the audio-visual presentation in a forward direction at a fast rate, and a reading of the fast-reverse file produces an MPEG transport stream of the audio-visual presentation in a reverse direction at a fast rate. Preferably, the files share a volume that includes at least one GOP index associating the corresponding I frames of the files.

Processing of MPEG encoded video for trick mode operation

Time stamps in an encoded digital motion video data stream (such as an MPEG Transport Stream) are re-stamped for seamless splicing. The re-stamping includes attainment of Presentation Time Stamp (PTS) agreement in the video stream, alignment of audio stream and video stream Presentation Time Stamps, and re-stamping of the Program Clock Reference (PCR) to eliminate jitter and to comply with MPEG standards. The MPEG compliance is achieved by padding, stuffing and insertion of freeze B and P frames and pre-encoded black I frames. Freeze frame insertion can be also achieved by replacing B and P frames by, smaller in size, freeze B and P frames respectively. No frames are discarded such that both spatial and temporal frame accuracy (no extra frame insertion assumed) is achieved. Moreover, padding is inserted into the data stream to compensate for irregularities in the decoder buffer level, and the audio and video buffer levels are managed dynamically to recover from data miss-delivery to minimize secondary effects, including prediction of errors, inducing freeze or skip, and insertion of padding. The start of the play of the second MPEG stream spliced to the first one is frame accurate and starts as scheduled based on the use of an external clock signal in a stream server computer.

Real time processing and streaming of spliced encoded MPEG video and associated audio

Predictive analysis is performed upon encoded digital motion video (such as an MPEG Transport Stream) to facilitate real-time splicing. The predictive analysis includes estimation of upper and lower bounds of the data levels in a decoder's video and audio buffers for splicing in such a way as to prevent buffer overflow and underflow. This enables buffer management techniques including padding or stuffing, micro-restamping, freeze or repeat of frames, skip or drop of frames, alignment of audio with video. The predictive analysis also includes analysis of the structure of the encoded audio including audio access units (AAUs) and compression windows (AFs), prediction in the compressed domain of initial conditions of the decoder buffer levels for every single Elementary Stream (ES) component of a Transport Stream (TS), and identification of valid splicing In Points and Out Points based on the predicted buffer levels without any special encoder. This permits splicing of different compressed audio types without consideration of the details of the compression mechanism. The predictive analysis may also include recommendations or marking. The analysis is performed on ingest of the data as a pre-processing in preparation for splicing of a new file on early queuing in a data storage system before streaming.

Growing community of inventors

Montigny-le-Bretonneux, France

Daniel Gardere