Method for seamless and near seamless audio and non-video splicing of a digital transport stream

In a system of implementing splicing of at least one audio and non-video data stream for predetermined video splice-in and splice-out points, a method for determining the audio splice-in point including the steps of:

• scanning a Single Program Transport Stream (SPTS) forward in time from the Video splice-in point;
• examining each audio packet encountered to determine whether it is the first audio frame after the video splice-in point;
• and
• replacing each audio packet encountered that is not a first audio frame with a null packet;
• whereby an audio splice-in point that supports a near-seamless audio splice is determined.

In an MPEG-2 system of splicing audio and non-video data streams, a method for determining an audio splice-in point comprising the steps of:

• scanning forward in time Until the first audio Packetized Elementary Stream (PES) header with an Audio PTS (Audio Presentation Time Stamp) (APTS) greater than the Video PTS (VPTS) is detected;
• continuing to scan audio packets until an audio frame header is detected;
• and
• replacing each audio packet encountered that does not contain this specific audio frame header (or Audio Packetized Elementary Stream header) with a null packet;
• whereby an audio splice-in point that supports a near-seamless audio splice is determined.

In a MEG-2 system of splicing at least one audio and non-video data stream, a method for determining the audio splice-out point comprising the steps of:

• scanning the SPTS backward in time from the video splice-out point;
• examining each audio packet thus encountered for the beginning of the first audio frame before a video splice-out point;
• and
• replacing each audio packet encountered that does not contain an audio frame header with a null packet;
• whereby an audio splice-out point that supports a near-seamless audio splice is determined.

A method for splicing of at least one audio and non-video data stream/comprising the steps of:

• scanning forward in time until the first audio packetized elementary stream (PBS) header with an audio PTS (APTS) greater than the video PTS (VPTS) is detected;
• continuing to scan audio packets until an audio frame header is detected;
• replacing each audio packet encountered that does not contain this specific audio frame header (or audio PES header) with a null packet;
• scanning forward in time until the last audio PES header with APTS<VPTS is detected;
• replacing each video packet between the video splice-out point and this point with a null packet;
• copying the audio packets for the old SPTS to an intermediate splice buffer;
• adding a constant to the PTS of the audio packets in the intermediate splice buffer where the constant is defined by:
• C=VPTS_NEW(FIRST)−[VPTS_OLD(LAST)+PICTURE_GAP]
• where:
• VPTS_NEW(FIRST) is the presentation time of the first video frame spliced in from the new SPTS;
• VPTS_OLD(LAST) is the presentation time of the last video frame of the old SPTS;
• PICTURE_GAP is calculated as the Ticks per Second divided by the number of pictures per second;
• replacing a combination of null packets and leading audio packets of the new SPTS with audio packets from the intermediate splice buffer;
• whereby a near-seamless audio splice is accomplished.

A method for seamless at least one splicing audio and non-video data stream, comprising the steps of;

• scanning forward in time until a first audio packetized elementary stream (PES) header with an audio PTS (APTS) greater than a video PTS (VPTS) is detected;
• continuing to scan audio packets until on audio frame header is detected;
• replacing each audio packet encountered that does not contain a specific audio frame header (or audio PES header) with a null packet;
• scanning forward in time until the last audio PES header with APTS<VPTS is detected;
• replacing each video packet between the video splice-out point and this point with one of said null packets;
• copying the audio packets for the old SPTS to an intermediate splice buffer;
• adding a constant to the PTS of the audio packets in said intermediate splice buffer, where said constant is determined by the relationship:
• C=VPTS_NEW(FIRST)−[VPTS_OLD(LAST)+PICTURE_GAP]
• where:
• VPTS_NEW(FIRST) is the presentation time of the first video frame spliced in from the new SPTS;
• VPTS_OLD(LAST) is the presentation time of the last video frame of the old SPTS;
• PICTURE_GAP is calculated as the Ticks per Second divided by the number of pictures per second;
• whereby an audio splice-in point to support a near-seamless audio splice is determined.