Abstract:
An image capture apparatus generates video data from captured images, and generates a video PES (packetized elementary stream) from the video data. The image capture apparatus converts the video PES into a MPEG-2 program stream, and converts the video PES into a MPEG-2 transport stream. The image capture apparatus records the MPEG-2 program stream on a random-access recording medium, and transmits the MPEG-2 transport stream to an external device. The conversion from the video PES into the MPEG-2 program stream and the conversion from the video PES into the MPEG-2 transport stream are performed in parallel thereby enabling the image capture apparatus to perform the recording of the MPEG-2 program stream and the transmission of the MPEG-2 transport stream in parallel.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an image capture apparatus, and more particularly, to an image capture apparatus such as a digital video camera. 
   BACKGROUND OF THE INVENTION 
   MPEG-2 Systems (see ISO/IEC 13818-1:2000, Information technology—Generic coding of moving pictures and associated audio information: Systems) prescribe PS (Program Stream; hereinafter “MPEG-2PS”, TS (Transport Stream; hereinafter “MPEG-2TS”) and PES (Packetized Elementary Stream). 
   In addition, for example, as described in Japanese Laid-Open Patent Publication No. 2000-138896, a recording apparatus having the capability to convert MPEG-2TS to MPEG-2PS and record the MPEG-2PS on a disk medium, as well as a recording apparatus having the capability to convert analog video signals and analog audio signals into MPEG-2PS and record the MPEG-2PS on a disk medium, have already been proposed. 
   Recent digital video cameras are required to have the following five capabilities: 
   (1) The ability to input and output MPEG-2TS and to record MPEG-2PS to, and to reproduce MPEG-2PS from, a random-access recording medium. 
   (2) The ability to generate MPEG-2PS and MPEG-2TS from captured images and input audio, and to record MPEG-2PS onto a random-access recording medium and to output MPEG-2TS to an external device. 
   (3) The ability to generate MPEG-2PS and MPEG-2TS from analog video signals and analog audio signals, and to record MPEG-2PS onto a random-access recording medium and to output MPEG-2TS to an external device. 
   (4) The ability to convert MPEG-2PS reproduced from a random-access recording medium into MPEG-2TS and output the MPEG-2TS to an external device. 
   (5) The ability to convert MPEG-2TS input from an external device into MPEG-2PS and record the MPEG-2PS onto a random-access recording medium. 
   However, no digital video camera having either one of these capabilities has been developed. 
   SUMMARY OF THE INVENTION 
   The present invention is conceived in consideration of the above-described conventional art, and has as its object to provide an image capture apparatus having at least one of the above-described capabilities. 
   According to an aspect of the present invention, there is provided an image capture apparatus comprising: input/output means for inputting and outputting an MPEG transport stream; recording/reproduction means for recording/reproducing an MPEG-2 program stream onto/from a random-access recording medium; and conversion means for converting the MPEG-2 transport stream into the MPEG-2 program stream, and converting the MPEG-2 program stream into the MPEG-2 transport stream. 
   According to another aspect of the present invention, there is provided an image capture apparatus comprising: program stream generating means for generating MPEG-2 program stream from a captured image and an input audio; transport stream generating means for generating MPEG-2 transport stream from the captured image and the input audio; and output means for outputting the MPEG-2 transport stream to an external device. 
   According to a further aspect of the present invention, there is provided an image capture apparatus comprising: program stream generating means for generating a MPEG-2 program stream from an analog video signal and an analog audio signal; transport stream generating means for generating a MPEG-2 transport stream from the analog video signal and the analog audio signal; and output means for outputting the MPEG-2 transport stream to an external device. 
   According to yet further aspect of the present invention, there is provided an image capture apparatus comprising: reproduction means for reproducing an MPEG-2 program stream from a random-access recording medium; conversion means for converting the MPEG-2 program stream into an MPEG-2 transport stream; and output means for outputting the MPEG-2 transport stream to an external device. 
   According to another aspect of the present invention, there is provided an image capture apparatus comprising: input means for inputting a MPEG-2 transport stream from an external device; conversion means for converting the MPEG-2 transport stream into a MPEG-2 program stream; and recording means for recording the MPEG-2 program stream onto a random-access recording medium. 
   Other features, objects and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a block diagram showing essential components of a digital video camera (DVC) that is an image capture apparatus according to one embodiment of the present invention; 
       FIG. 2  is a flow chart illustrating an example of the operation of a DVC when the DVC is in a camera mode; 
       FIG. 3  is a flow chart illustrating an example of the operation of a DVC when the DVC is in a digital output mode; 
       FIG. 4  is a flow chart illustrating an example of the operation of a DVC when the DVC is in a digital input mode; and 
       FIG. 5  is a flow chart illustrating an example of the operation of a DVC when the DVC is in an analog input mode. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. It should be noted that the present embodiment uses PS, TS and PES stipulated by the MPEG-2 Systems. 
   FIRST EMBODIMENT 
   In order to facilitate an understanding of the present invention, a description is first given of the main component parts of a digital video camera (DVC)  10  that is an image capture apparatus according to one embodiment of the present embodiment, with reference to  FIG. 1 . As can be appreciated by those of ordinary skill in the art, the present invention can also be adapted to image capture apparatuses other than digital video cameras. 
   A camera unit  101 , which generates video data from captured images, is comprised of an optical system including a lens, image capturing device and their associated control circuits. A microphone  102  generates audio data from input audio. 
   An AV encoder  103  encodes video data output from the camera unit  101  or an analog video I/O  115  as video ES (video Elementary Stream) and converts the video ES to video-use PES (hereinafter “video PES”). The AV encoder  103  also encodes audio data output from the microphone  102  or an analog audio I/O  116  as audio ES (audio Elementary Stream) and converts the audio ES into audio-use PES (hereinafter “audio PES”). 
   It should be noted that the video encoding scheme used in generating video ES may, for example, be MPEG-2 Video (see ISO/IEC 13818-2: 2000, Information technology—Generic coding of moving pictures and associated audio information: Video). In addition, the audio encoding scheme used in generating audio ES may, for example, be MPEG-2 Audio BC (see ISO/IEC 13818-3: 1998, Information technology—Generic coding of moving pictures and associated audio information—Part 3: Audio), MPEG-2 Audio LSF (see ISO/IEC 13818-3: 1998), or MPEG-2 Audio AAC (see ISO/IEC 13818-7: 1997, Information technology—Generic coding of moving pictures and associated audio information—Part 7: Advanced Audio Coding (AAC)). 
   A PES/PS converter  104  converts video PES and audio PES output from the AV encoder  103  or the PES/TS converter  110  into MPEG-2PS (MPEG-2 program stream), and also converts the MPEG-2PS output from a recording/reproduction unit  105  into video PES and audio PES. 
   The recording/reproduction unit  105  records MPEG-2PS output from the PES/PS converter  104  onto a recording medium  106 , and also reproduces MPEG-2PS designated by a control unit  114  from the recording medium  106 . The recording medium  106  may be a random-access recording medium such as a disk, a semiconductor memory or the like. 
   An AV decoder  107  converts video PES output from the AV encoder  103  or the PES/PS converter  104  and decodes the video ES into video data. The AV decoder  107  also converts audio PES output from the AV encoder  103  or the PES/PS converter  104  into audio ES, and decodes the audio ES into audio data. 
   A display unit  108  displays video data output from the camera unit  101  or the AV decoder  107 , and is comprised of a display device such as an LCD, for example. A speaker  109  outputs audio data output from the microphone  102  or the AV decoder  107 . 
   A PES/TS converter  110  converts video PES and audio PES output from the AV encoder  103  or the PES/PS converter  104  into MPEG-2TS, and converts MPEG-2TS output from a digital communications unit  111  into video PES and audio PES. 
   The digital communications unit  111  outputs MPEG-2TS output from the PES/TS converter  110  to an external device, and inputs MPEG-2TS from an external device. It should be noted that the digital communications unit  111  may, for example, conform to IEEE 1394 standard (including IEEE 1394-1995, IEEE 1394a-2000 and extensions thereof) or USB standard (including USB 2.0 standard and extensions thereof). 
   A memory  112  stores a play list that the control unit  114  generates according to user instructions. A play list is a list that specifies how a plurality of MPEG-2PS recorded on the recording medium  106  are to be reproduced. For example, with a play list it is possible to specify a reproduction sequence or order for a plurality of MPEG-2PS and a reproduction starting point and a reproduction ending point for each of the MPEG-2PS. 
   An operations panel  113  sends user instructions to the control unit  114  and comprises a variety of input devices such as buttons, keys, touch panels and jog dials are used as appropriate. The control unit  114  controls the functions of the DVC  10 . 
   The analog video I/O  115  converts analog video signals input from an external source into video data, and converts video data output from the camera unit  101  and the AV decoder  106  into analog video signals and outputs the analog video signals to an external device. 
   The analog audio I/O  116  converts analog audio signals input from an external device into audio data, and converts audio data input from the microphone  102  or the AV decoder  106  into analog audio signals and outputs the analog audio signals to an external device. 
   (1) Camera Mode 
   Next, a description is given of an example of operations of a DVC  10  when the DVC  10  is in a camera mode, with reference to the flow chart in  FIG. 2 . 
   In a step S 201 , when a user uses the operations panel  113  to turn the camera mode on, the control unit  114  reports the start of the camera mode to the components. In response to such notification, the components start predetermined operations. In other words, the camera unit  101  starts to generate video data from captured images and the microphone  102  starts to generate audio data from input audio. The display unit  108  starts to display video data output from the camera unit  101 . The speaker  109  starts to output audio data output from the microphone  102 . The analog video I/O  115  starts to convert video data output from the camera unit  101  into analog video signals and outputs the analog video signals to an external device. The analog audio I/O  116  starts to convert audio data output from the microphone  102  into analog audio signals and outputs the analog audio signals to an external device. 
   In a step S 202 , the AV encoder  103  starts to encode video data output from the camera unit  101  as video ES and convert the video ES into video PES. At the same time, the AV encoder  103  starts to encode audio data output from the microphone  102  as audio ES and convert the audio ES into audio PES. 
   In a step S 203 , the PES/PS converter  104  starts to convert the video PES and the audio PES output from the AV encoder  103  into MPEG-2PS. At the same time, the PES/TS converter  110  starts to convert the video PES and the audio PES output from the AV encoder  103  into MPEG-2TS. That is, the DVC  10  can simultaneously generate MPEG-2PS and MPEG-2TS from the captured images and the input audio. The digital communications unit  111  starts to output MPEG-2TS output from the PES/TS converter  110  to an external device. The recording/reproduction unit  105  waits to record MPEG-2PS onto the recording medium  106  until there is an instruction to start recording. 
   In a step S 204 , the control unit  114  determines whether or not an instruction to start recording has been issued by determining, for example, whether or not a REC button (that is, a recording start/stop button) on the operations panel  113  has been pressed. Processing proceeds to a step S 205  if it is detected that the REC button has been pressed. 
   In a step S 205 , the control unit  114  sends an instruction to start recording to the recording/reproduction unit  105 . The recording/reproduction unit  105  starts to record the MPEG-2PS output from the PES/PS converter  104  to the recording medium  106 . 
   Thus, a DVC  10  according to this embodiment can generate MPEG-2TS and MPEG-2PS from the captured image and the input audio, and output the generated MPEG-2TS to an external device and output the generated MPEG-2PS to the recording medium  106 . 
   In addition, the DVC  10  according to this embodiment can simultaneously generate MPEG-2PS from captured images and input audio and MPEG-2TS from captured images and input audio. 
   (2) Digital Output Mode 
   Next, a description is given of the operations of the DVC  10  when the DVC  10  is in a digital output mode, with reference to the flow chart of  FIG. 3 . 
   In a step S 301 , when a user uses the operations panel  113  to turn the digital output mode on, the control unit  114  reports the start of the digital output mode to the components. The control unit  114  selects the MPEG-2PS to be reproduced in accordance with a user instruction or a play list, and notifies the selected MPEG-2PS to the recording/reproduction unit  105 . The recording/reproduction unit  105  reproduces the MPEG-2PS designated by the control unit  114  at normal speed from the recording medium  106 . The PES/PS converter  104  converts the MPEG-2PS output from the recording/reproduction unit  105  into video PES and audio PES. The AV decoder  106  converts video PES output from the PES/PS converter  104  to video ES and starts to decode the video ES into video data, and at the same time converts the audio PES output from the PES/PS converter  104  into audio ES and starts decoding the audio ES into audio data. The display unit  108  starts to display video data output from the AV decoder  106 . The speaker  109  starts to output audio data output from the AV decoder  106 . The analog video I/O  115  starts to convert video data output from the AV decoder  106  into analog video signals and output the analog video signals to an external device. The analog audio I/O  116  starts to convert audio data output from the AV decoder  106  into analog audio signals and output the analog audio signals to an external device. 
   In a step S 302 , the control unit  114  determines whether or not to prohibit TS conversion (that is, converting MPEG-2PS into MPEG-2TS). In this embodiment, TS conversion of MEPG-2PS is prohibited when attribute information prohibiting the TS conversion is attached to the MPEG-2PS output from the recording/reproduction unit  105 . If TS conversion is prohibited, then processing proceeds to a step S 303 . If TS conversion is not prohibited, then processing proceeds to a step S 304 . 
   In step S 303  the control unit  114  prohibits TS conversion. In such a case, the DVC  10  outputs a null packet (that is, a packet without a payload, or a packet of which payload contains invalid data) from the digital communications unit  111 . 
   In step S 304 , the control unit  114  permits TS conversion. 
   In a step S 305 , the control unit  114  determines whether or not to execute encryption (that is, to encrypt MPEG-2TS) and sends the results of that determination to the PES/TS converter  110 . In this embodiment, the control unit  114  determines to execute encryption if attribute information that requests encryption is attached to the MPEG-2PS output from the recording/reproduction unit  105 . If encryption is to be executed, then processing proceeds to a step S 306 . If encryption is not to be executed, then processing proceeds to a step S 307 . 
   In step S 306 , the PES/TS converter  110  starts to convert video PES and audio PES output from the PES/PS converter  104  into MPEG-2TS, and at the same time starts to encrypt the MPEG-2TS payload. The digital communications unit  111  starts to output the MPEG-2TS encrypted by the PES/TS converter  110  to an external device. 
   In step S 307 , the PES/TS converter  110  starts to convert the video PES and the audio PES output from the PES/PS converter  104  into MPEG-2TS. Here, the MPEG-2TS payload is not encrypted. The digital communications unit  111  starts to output the MPEG-2TS output from the PES/TS converter  110  to an external device. 
   In a step S 308 , the control unit  114  determines whether or not there is an MPEG-2PS to be reproduced next. If the user specifies an MPEG-2PS to be reproduced next, or if there is still MPEG-2PS to be reproduced on the play list, then the control unit  114  determines that there is MPEG-2PS to be reproduced next, in which case the process returns to step S 301 . 
   Thus, the DVC  10  according to the present embodiment can convert MPEG-2PS reproduced from the recording medium  106  into MPEG-2TS according to a user instruction or a play list and output the MPEG-2TS to an external device. 
   In addition, the DVC  10  according to this embodiment, when TS conversion of the MPEG-2PS reproduced from the recording medium  106  is prohibited, thus the conversion of that MPEG-2PS into MPEG-2TS can be prohibited. In this case, the DVC  10  can output a null packet (that is, a packet without a payload or a packet of which payload contains invalid data) from the digital communications unit  111 . 
   In addition, the DVC  10  according to the embodiment described above can encrypt and output MPEG-2TS. 
   It should be noted that the DVC  10  according to this embodiment can reproduce the MPEG-2PS fast or slow. In this case, the PES/TS converter  110  may convert video PES, obtained either at intervals or repeatedly, into MPEG-2TS, or, alternatively, I pictures may be extracted from the MPEG-2PS obtained either at intervals or repeatedly and MPEG-2TS may be generated from the extracted I pictures. 
   (3) Digital Input Mode 
   Next, a description is given of the operation of the DVC  10  when the DVC  10  is in a digital input mode, with reference to the flow chart of  FIG. 4 . 
   In a step S 401 , when the user uses the operations panel  113  to turn the digital input mode on, the control unit  114  reports the start of the digital input mode to the component parts. The digital communications unit  111  starts to input the MPEG-2TS selected by the user from an external device. 
   In a step S 402 , the PES/TS converter  110  starts to convert the MPEG-2TS output from the digital communications unit  111  into video PES and audio PES. The AV decoder  107  starts to convert the video PES output from the PES/TS converter  110  into video ES and decode that video ES into video data. In addition, the AV decoder  107  also starts to convert the audio PES output from the PES/TS converter  110  into audio ES and decode that audio ES into audio data. The display unit  108  starts to display the video data output from the AV decoder  107 . The speaker  109  starts to output audio data output from the AV decoder  107 . The analog video I/O  115  starts to convert video data output from the AV decoder  107  into analog video signals and output those analog video signals to an external unit. The analog audio I/O  116  starts to convert audio data output from the AV decoder  107  into analog audio signals and output those analog audio signals to an external device. 
   In a step S 403 , the control unit  114  determines whether or not it is necessary to change at least one of either the number of pixels (also called the resolution), the frame rate (that is, the number of frames per second), the compression rate, the sampling frequency or the audio coding method. In the present embodiment, if the user inputs to the DVC  10  an instruction to change at least one of a preset number of pixels, frame rate, compression rate, sampling frequency or audio coding method, the control unit  114  determines that a change is necessary and reports the content of the change to the AV decoder  107 . If change is necessary, then processing proceeds to a step S 404 . If no change is necessary, then processing proceeds to a step S 406 . 
   In step S 404 , if it is necessary to change at least one of either the number of pixels, the frame rate or the compression rate, the AV decoder  107  starts to change at least one of the number of pixels, frame rate or compression rate of the video data in response to notification from the control unit  114 . On the other hand, if it is necessary to change at least one of either the sampling frequency or the audio coding method, the AV decoder  107  starts to change at least one of the sampling frequency or the audio coding method. The AV encoder  103  starts to encode video data output form the AV decoder  107  to video ES and in turn the video ES to video PES. The AV encoder  103  also starts to encode audio data output from the AV decoder  107  to audio ES and in turn the audio ES to audio PES. 
   In a step S 405 , the PES/PS converter  104  starts to convert video PES and audio PES output from the AV encoder  103  into MPEG-2PS. 
   In step S 406 , the PES/ES converter  104  starts to convert video PES and audio PES output from the PES/TS converter  110  into MPEG-2PS. 
   In a step S 407 , the control unit  114  determines whether or not an instruction to start recording has been issued, for example, by determining whether or not the REC button has been pressed. If the control unit  114  detects that the REC button has been pressed, then processing proceeds to a step S 408 . 
   In step S 408 , the control unit  114  sends the instruction to start recording to the recording/reproduction unit  105 . The recording/reproduction unit  105  starts to record the MPEG-2PS output from the PES/PS converter  104  onto the recording medium  106 . 
   As described above, the DVC  10  according to the present embodiment can convert MPEG-2TS input from an external device into MPEG-2PS and records the MPEG-2PS on a recording medium  106 . 
   In addition, the DVC  10  according to the present embodiment can change the number of pixels, frame rate and compression rate of the video data obtained from the MPEG-2TS when converting MPEG-2TS into MPEG-2PS and recording the MPEG-2PS onto the recording medium  106 . For example, the DVC  10  can change the number of pixels from 1920×1080 pixels to 720×480 pixels, and can change the frame rate from 60 Hz (60 frames/second) to 30 Hz (30 frames/second). 
   In addition, the DVC  10  according to the present embodiment can change the audio data sampling frequency and audio coding mode of the audio data obtained from the MPEG-2TS when converting the MPEG-2TS into MPEG-2PS, and recording the MPEG-2PS onto the recording medium  106 . For example, the DVC  10  can change the sampling frequency from 48 kHz to 32 kHz, and can change the audio coding method from MPEG-2 Audio BC to MPEG-2 Audio AAC. 
   (4) Analog Input Mode 
   Next, a description is given of the operation of a DVC  10  when the DVC  10  is in an analog input mode, with reference to the flow chart of  FIG. 5 . 
   In a step S 501 , when a user uses the operations panel  113  to turn the analog input mode on, the control unit  114  reports the start of the analog input mode to the components. The analog video I/O  115  starts to convert the analog video signals input from an external device into video data and output the video data to the AV encoder  103  and the display unit  108 . The analog audio I/O  116  starts to convert the analog audio signals input from an external device into audio data and output the audio data to the AV encoder  103  and the speaker  109 . The display unit  108  starts to display the video data output from the analog video I/O  115 . The speaker  109  starts to output the audio data output from the analog audio I/O  116 . 
   In a step S 502 , the AV encoder  103  starts to encode the video data output from the analog video I/O  115  as video ES and converts the video ES into video PES. At the same time, the AV encoder  103  starts to encode the audio data output from the analog audio I/O  116  as audio ES and convert that audio ES into audio PES. 
   In a step S 503 , the PES/PS converter  104  starts to convert the video PES and audio PES output from the AV encoder  103  into MPEG-2PS. On the other hand, the PES/TS converter  110  starts to convert the video PES and audio PES output from the AV encoder  103  into MPEG-2TS. That is, the DVC  10  can simultaneously generate MPEG-2PS as well as MPEG-2TS from the analog video signals and analog audio signals. The digital communications unit  111  starts to output MPEG-2TS output from the PES/TS converter  110  to an external device. The recording/reproduction unit  105  waits for an instruction to start recording to record the MPEG-2PS onto the recording medium  106 . 
   In a step S 504 , the control unit  114  determines whether or not an instruction to start recording has been issued, for example by determining whether or not the REC button has been pressed. If the control unit  114  detects that the REC button has been pressed, then processing proceeds to a step S 505 . 
   In step S 505 , the control unit  114  reports the instruction to start recording to the recording/reproduction unit  105 . The recording/reproduction unit  105  then starts to record the MPEG-2PS output from the PES/PS converter  104  onto the recording medium  106 . 
   As described above, the DVC  10  according to the present embodiment can generate MPEG-2TS and MPEG-2PS from analog video signals and analog audio signals, and can output the generated MPEG-2TS to an external device and can record the generated MPEG-2PS to the recording medium  106 . 
   In addition, the DVC  10  according to the present embodiment can simultaneously generate MPEG-2PS as well as MPEG-2TS from analog video signals and analog audio signals. 
   OTHER EMBODIMENTS 
   As can be appreciated by those of ordinary skill in the art, the present invention is not limited to the embodiment described above but can be adapted to other embodiments as well. 
   Thus, for example, the present invention may be adapted to an embodiment that combines a menu screen, warning mark or other image data with the video data prior to converting the video data output from the camera unit  101  or the AV decoder  107  into MPEG-2TS and outputting the MPEG-2TS to an external device. 
   According to the image capture apparatus of the above embodiments, it is possible to input and output MPEG-2TS, and record and reproduce MPEG-2PS. 
   In addition, according to the image capture apparatus of the above embodiments, it is possible to generate MPEG-2 program stream (PS) and MPEG-2 transport stream (TS) from captured images and input audio. 
   In addition, according to the image capture apparatus of the above embodiments, it is possible to generate MPEG-2 program stream and MPEG-2 transport stream from analog video signals and analog audio signals. 
   In addition, according to the image capture apparatus of the above embodiments, it is possible to convert an MPEG-2 program stream reproduced from a random-access recording medium into an MPEG-2 transport stream and output the MPEG-2 transport stream to an external device. 
   In addition, according to the image capture apparatus of the above embodiments, it is possible to convert an MPEG-2 transport stream input from an external device into an MPEG-2 program stream and record the MPEG-2 program stream onto a random-access recording medium  106 . 
   As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.