Seamless switching of MPEG video streams

• US 6,628,712 B1
• Filed: 11/08/2000
• Issued: 09/30/2003
• Est. Priority Date: 11/23/1999
• Status: Expired due to Term

• Current Assignee: Uniloc 2017 LLC (FIG LLC (d/b/a Fortress Investment Group LLC))
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Le Maguet, Yann
• Primary Examiner(s): Le, Vu
• Application Number:
  US09/708,165
• Time in Patent Office: 1,056 Days
• Field of Search: 375/240.02, 375/240.1, 375/240.12, 375/240.16, 375/240.13, 375/240.14, 375/240.15, 375/240.25, 375/240.26, 348/423.1, 348/425.1, 348/425.3, 348/416.1, 386/111, 382/235-236, 382/238, 358/261.2, 358/430
• US Class Current: 375/240.12
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 21/23424 involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
• CPC Class Codes: H04N 21/2343 involving reformatting operations of video signals for distribution or compliance with end-user requests or end-user device requirements video transcoding H04N19/40; media packet handling at the source H04L65/762
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip

Abstract

A switching device SW allows to switch from a first compressed data input stream IS1 to a second compressed data input stream IS2, resulting in a compressed data output stream OS. This switching device comprises a buffer system BS intended to store the data contained in the first and second input streams, and control means CONT which controls the storage of the input streams in the buffer system in order to switch, at a switch request SWR, from the first input stream to the second input stream, using a commutation device COM.

A transcoding system TS is intended to receive the data stream at the output of the commutation device and to provide the output stream in a seamless way. The use of a transcoding system allows to avoid an underflow or an overflow of the buffer of the decoder that will have to decode the output stream. Moreover, said transcoding system allows to encode the output stream at a bit rate R, where R may be different from the bit rate R1 of the first input stream and the bit rate R2 of the second input stream.

Claims

1. A device for switching (SW) from a first compressed data input stream (IS1) to a second compressed data input stream (IS2), resulting in a compressed data output stream (OS), said switching device comprising:

a buffer system (BS) to store the data contained in the first and second input streams,

control means (CONT) to control the storage of the input streams in the buffer system in order to switch, at a switch request (SWR), from the first input stream to the second input stream using a commutation device (COM),

and a transcoding system (TS) including a quantization block and a buffer, wherein occupancy of the buffer in the transcoding system is controlled by feedback to the quantization block to provide the output stream in a seamless way from the output of the commutation device.

2. A switching device for switching (SW) from a first compressed data input stream (IS1) to a second compressed data input stream (IS2), resulting in a compressed data output stream (OS), said switching device comprising:

a buffer system (BS) intended to store the data contained in the first and second input streams,

control means (CONT) to control the storage of the input streams in the buffer system in order to switch, at a switch request (SWR), from the first input stream to the second input stream using a commutation device (COM),

and a transcoding system (TS) to provide the output stream in a seamless way from the output of the commutation device,

wherein the buffer system comprises a first buffer (BUF1) and a second buffer (BUF2) intended to store the data contained in the first and the second input stream, respectively,

wherein the transcoding system comprises one transcoder,

the commutation device is controlled to switch from the output of the first buffer to the output of the second buffer when said first buffer has transmitted a set of M pictures of the first input stream, said second buffer being controlled by the control means to transmit an I picture,

and said switching device comprises means for generating B pictures without forward predictions for a set of M pictures of the second input stream including said I picture.

3. A switching device for switching (SW) from a first compressed data input stream (IS1) to a second compressed data input stream (IS2), resulting in a compressed data output stream (OS), said switching device comprising:

a buffer system (BS) to store the data contained in the first and second input streams,

control means (CONT) to control the storage of the input streams in the buffer system in order to switch, at a switch request (SWR), from the first input stream to the second input stream using a commutation device (COM),

and a transcoding system (TS) to provide the output stream in a seamless way from the output of the commutation device,

wherein the buffer system comprises a first buffer and a second buffer intended to store the data contained in the first and the second input stream, respectively,

wherein the transcoding system comprises, in association with each input stream, first means for decoding and second means for decoding,

the commutation device is controlled to switch from the first input stream after decoding by the first means to the second input stream after decoding by the second means when the first buffer has transmitted a set of M pictures of the first input stream, the second buffer being controlled by the control means to transmit an I picture or a P picture, which is re-encoded as an I picture using decoding-encoding means,

and said switching device comprises means for generating B pictures without forward predictions for a set of M pictures of the second input stream including said I picture.

4. A method of switching from a first compressed data input stream to a second compressed data input stream, resulting in a compressed data output stream, said method of switching comprising the steps of:

buffering, in which the data contained in the first and the second input stream are stored,

controlling the storage of the input streams during the buffering step in order to switch, at a switch request, from the first input stream to the second input stream,

transcoding the stream provided by the control step, the transcoding includes controlling occupancy of a buffer by feedback to DCT coefficient quantization in order to provide the output stream in a seamless way.

5. A method of switching from a first compressed data input stream to a second compressed data input stream, resulting in a compressed data output stream, said method of switching comprising the steps of:

buffering, in which the data contained in the first and the second input stream are stored,

controlling the storage of the input streams during the buffering step in order to switch, at a switch request, from the first input stream to the second input stream,

transcoding the stream provided by the control step in order to provide the output stream in a seamless way,

wherein the transcoding step comprises one transcoding channel,

the control step allows to switch, at a switch request, from the first input stream to the second input stream when the buffering step has transmitted a set of M pictures of the first input stream, the buffering step being controlled to transmit an I picture,

and said method of switching comprises a step of generating B pictures without forward predictions for a set of M pictures of the second input stream including said I picture.

6. A method of switching from a first compressed data input stream to a second compressed data input stream, resulting in a compressed data output stream, said method of switching comprising the steps of:

buffering, in which the data contained in the first and the second input stream are stored,

controlling the storage of the input streams during the buffering step in order to switch, at a switch request, from the first input stream to the second input stream,

transcoding the stream provided by the control step in order to provide the output stream in a seamless way

wherein the transcoding step comprises a first sub-step of decoding the first input stream and a second sub-step of decoding the second input stream,

the control step allows to switch, at a switch request, from the first input stream after the first decoding step to the second input stream after the second decoding step when the buffering step has transmitted a set of M pictures of the first input stream, the buffering step being controlled to transmit an I picture or a P picture, which is re-encoded as an I picture using a decoding-encoding step,

and said method of switching comprises a step of generating B pictures without forward predictions for a set of M pictures of the second input stream including said I picture.

7. A device for switching (SW) from a first compressed data input stream (IS1) to a second compressed data input stream (IS2), resulting in a compressed data output stream (OS), said switching device comprising:

a buffer system (BS) intended to store the data contained in the first and second input streams,

control means (CONT) intended to control the storage of the input streams in the buffer system in order to switch, at a switch request (SWR), from the first input stream to the second input stream using a commutation device (COM),

and a transcoding system (TS) intended to provide the output stream in a seamless way from the output of the commutation device,

means for generating B pictures without forward predictions for a set of M pictures of the second input stream including an I picture.

8. A method of switching from a first compressed data input stream to a second compressed data input stream, resulting in a compressed data output stream, said method of switching comprising the steps of:

buffering, in which the data contained in the first and the second input stream are stored,

controlling the storage of the input streams during the buffering step in order to switch, at a switch request, from the first input stream to the second input stream,

transcoding the stream provided by the control step in order to provide the output stream in a seamless way,

generating B pictures without forward predictions for a set of M pictures of the second input stream including an I picture.