摘要:
A statistical multiplexer for coding and multiplexing multiple channels of digital television data, or multiple panels of HDTV digital television data. A bit rate need parameter is determined for each encoder in a stat mux group by scaling the complexities of previous pictures of the same and different picture types. Scaling factors based on an activity level, motion estimation score, and number of pictures of a certain type in a GOP, may be used. Moreover, the scaling factors may be bounded based on a linear or non-linear operator to prevent large variations in the factors. An encoding bit rate is allocated to each channel based on its need parameter.
摘要:
Coding may include receiving a source video bitstream including source frames and determining information from the source frames. The determined information may include timing information and grouping information and may be utilized in encoding synchronizing processed frames for a synchronized compressed video bitstream. Decoding may include receiving a synchronized compressed video bitstream including the encoding synchronizing processed frames. The decoding may include preparing video chunk files having boundaries defined by the encoding synchronizing processed frames and decoding the prepared video chunk files.
摘要:
A statistical multiplexer for coding and multiplexing multiple channels of digital television data, or multiple panels of HDTV digital television data. A bit rate need parameter is determined for each encoder in a stat mux group, and an encoding bit rate is allocated to each channel based on its need parameter. A transmission bit rate is allocated to each channel as a time-lagged version of its need parameter to minimize a rate mismatch between the output and the input of a decoder buffer. A packet processor checks for impending decoder buffer overflow or underflow events to set minimum and maximum limits on the transmission bit rate. Moreover, these limits are set based on whether a new transmission bit rate can be implemented before the decoding time stamp (DTS) of the current or next frame.
摘要:
A detector for determining an audio data bit rate of a pre-compressed audio elementary stream (AES), in which the pre-compressed AES includes a plurality of preamble length fields is provided. The detector includes an analyzer module configured to determine one or more candidate audio data bit rates of the AES from the plurality of preamble length fields, a detector module configured to determine whether one or more of the candidate audio data bit rates are correct, and a selector module configured to select one of the one or more candidate audio data bit rates determined to be correct as the audio data bit rate of the pre-compressed AES.
摘要:
A detector for determining an audio data bit rate of a pre-compressed audio elementary stream (AES), in which the pre-compressed AES includes a plurality of preamble length fields is provided. The detector includes an analyzer module configured to determine one or more candidate audio data bit rates of the AES from the plurality of preamble length fields, a detector module configured to determine whether one or more of the candidate audio data bit rates are correct, and a selector module configured to select one of the one or more candidate audio data bit rates determined to be correct as the audio data bit rate of the pre-compressed AES.
摘要:
An efficient statistical remultiplexer for processing a number of channels that include video data. In one aspect, transcoding of the video data is delayed while statistical information is obtained from the data. Bit rate need parameters for the data are determined based on the statistical information, and the video data is transcoded based on the respective bit rate need parameters following the delay. In another aspect, a transcoding bit rate for video frames is updated a plurality of times at successive intervals to allow a closer monitoring of the bit rate. Minimum and maximum bounds for the transcoding bit rate, e.g., for buffer overflow and underflow protection, are also updated in each interval. In another aspect, the pre-transcoding quantization scales of the macroblocks in a frame are scaled to provide corresponding new quantization scales for transcoding based on a ratio of a pre-transcoding amount of data in the frame and a target, post-transcoding amount of data for the frame. The quantization scales are adjusted for different portions of the frame as transcoding progresses to ensure that a minimum amount of transcoding bandwidth is allocated to each macroblock.
摘要:
An efficient processing system, such as for transcoding video data. In an embodiment that is suitable for single or multiple processor embodiments, a processing mode is set for each input video frame, e.g., as a full transcode mode, which uses motion compensation, a requantization mode, which avoids motion compensation, or a bypass mode. The processing mode selection is based on a number of processing cycles that are available to process a frame, and an expected processing requirement of the frame. The bypass or requantization modes are selected to avoid a buffer overflow of the processor.
摘要:
A system for providing an accurate time reference for multiple input and output digital video signals of a transcoder that is particularly suited for use with MPEG data. The multiple streams are synchronized with a single master system time clock at the transcoder. Timing data from the master clock is compared to timing data from packets that are input to the transcoder to determine an offset. In particular, timing data, such as a program clock reference (PCR) field, is recovered from packets of different channels that are input to the transcoder. For each channel, timing data is then provided for packets that are output from the transcoder based on the offset and timing data of the master clock at the respective output times. In particular, the adjusted timing data is determined as a sum of the offset and an associated hardware error, less a delay (PcrSysDly) associated with the transcoder, which includes a lookahead delay and a buffer delay. The associated hardware error represents an error of the master clock and/or a system time clock of an encoder that encoded the particular channel.
摘要:
A mechanism for splicing advertisements, local programming and the like into a digital video transport stream is provided. In order to achieve proper splicing, an appropriate number of frames is inserted between bitstreams to properly close a GOP of the first bitstream into which a second bitstream carrying the spliced content is inserted. Program clock references (PCRs) of the bitstreams are adjusted as necessary in order to force continuity between the bitstreams. For inserting advertisements, the PCR of the program stream and ad stream can be tracked, and the PCR of the program stream can be used both before and after splicing. For local program insertion (which are typically substantially longer than advertisements), the PCR of the local program can be used, after adjustment thereof with an offset to maintain continuity at the splice point. The PTS and/or DTS of the inserted bitstream can be modified to keep them continuous at the splice point for both video and audio streams. The spliced bitstream is transcoded to maintain a desired output bit rate, and to provide overflow/underflow protection of the video buffers.
摘要:
A method and apparatus for processing a bitstream in a digital video transcoder is described. In one example, an adjustment factor is determined that relates a number of bits representing a selected frame defined by the bitstream to a target number of bits for the selected frame. An average spatial activity value among sets of video data is associated with the selected frame. A spatial activity value for a selected set of the sets of video data is determined. A normalized spatial, activity value for the selected set of frequency video data is then computed in response to the average spatial activity value, the spatial activity value, and a function of the adjustment factor. Target bit reduction for each of the sets of video data may be computed using a function of the normalized spatial activity value and the adjustment factor.