Method per performing special effects in the receiver of a coded moving picture transmission system

Abstract: A moving picture is transmitted without bringing about a decline in compression efficiency and a deterioration in picture quality due to coding/decoding. On the basis of effect-designating data (S13) that has been received, a terminal on the receiving side performs the designated effect on the picture data which has been obtained by decoding coded data received from a common transmission line (S19), and displays the edited image data on a display unit.

Description: This invention relates to a method and apparatus for moving-picture processing and, more particularly, to a moving-picture processing method and apparatus for subjecting a moving picture to such editing as transition effect, etc. When digital moving-picture data is edited, compressed and transmitted in the prior art, the general practice is to edit the moving-picture data and then compress the moving-picture data that has been processed. It should be noted that the term "editing" as used here means superimposing a character, figure or the like on a moving picture or subjecting a moving picture to a transition effect, described below. The transition effect is processing for the purpose of smoothly connecting two moving-picture sequences that are continuous in terms of time and involves causing the moving picture that is earlier in time to fade out while causing the moving picture that is later in time to fade in. In this case, an image having a special state in which the two moving-picture sequences are superimposed appears within a range designated in a transition interval. The edited moving-picture data thus obtained is coded by any moving-picture coding method available and the coding data is transmitted to the receiving side through a communication line. The coded data received is decoded and displayed on the receiving side. Figs. 2A, 2B are flowcharts illustrating procedures for editing moving pictures according to the prior art, in which Fig. 2A shows the procedure performed by the terminal on the transmitting side and Fig. 2B the procedure performed by the terminal on the receiving side. According to the flowchart shown in Fig. 2A, the terminal on the transmitting side enters the moving-picture data and stores it in a memory at step S1. Next, the terminal on the transmitting side accepts an effect designation, such as a designation of the transition effect, at step S2, after which the terminal edits the moving-picture data, which has been stored in the memory, on the basis of the designation accepted at step S2. This is followed by step S4, at which the terminal on the transmitting side codes the edited moving-picture data, and then by step S5, at which the terminal transmits the coded data. Next, according to the flowchart shown in Fig. 2B, the terminal on the receiving side receives the coded data at step S6. Then, at step S7, the terminal on the receiving side decodes the coded data received and stores the moving-picture data thus decoded in a memory. The terminal on the receiving side displays the moving picture on a display unit at step S8. However, the technique described above involves a number of problems. Specifically, in the above-described technique, the edited image data that has been subjected to the transition effect or the like is coded. However, in the conventional moving-picture coding method that performs compression utilizing the correlation of mutually adjacent frames, the frame correlation is lost and efficient compression is difficult when it is attempted to compress special image data that has been subjected to the transition effect or the like. Further, according to some moving-picture coding methods, data is transmitted upon being thinned out and coded at a frame rate of ten frames per second in order to achieve a rate of compression. However, in the case of a moving picture having a low frame rate, a smooth transition effect is difficult to realize and the transition of the picture becomes too jerky. US Patent No. 5,227,875 discloses a video conferencing system in which the image data may be encoded together with letter message data, in order to display a superimposed message with the image. Said video conferencing system comprises receiving means adapted to receive from a transmission line additionally to encoded digital moving picture data a image size change rate information to be applied to image decoding means. The above mentioned U.S. patent was not published prior to the filing date hereof but corresponding Japanese Patent Applications JP-A-4100379 and JP-A-4192696 were published before the priority date hereof. EP-A-0330732 discloses a subtitling system for use in conjunction with analogue recording media (video compact disc). It allows user selection of one of a plurality of image data (e.g. different language subtitles) to be superimposed upon the picture image produced when playing the recording medium. An object of the present invention is to prevent a deterioration in picture quality, while enabling a range of effects to be provided. According to the present invention, there is disclosed a moving picture processing apparatus comprising: receiving means operable receive from a transmission line encoded digital moving picture data representing a moving picture; and decoding means operable to decode the encoded digital moving picture data; said receiving means is adapted also to receive, from said transmission line, command data including a command for commanding transition effect processing characterised in that : said transition effect processing is to be applied to the decoded moving picture data; and in that said apparatus further comprising processing means operable to subject the decoded moving picture data to said transition effect processing in accordance with the received command so as to effect said transition effect processing. An other aspect of the invention provides a method of processing a moving picture comprising the steps of: receiving from a transmission line encoded digital moving picture data representing a moving picture; and decoding the encoded digital moving picture data; said receiving step is adapted to receive from said transmission line command data including a command for commanding transition effect processing characterised in that : said transition effect processing is to be applied to the decoded moving picture data; and in that the method further comprises: a processing step subjecting the decoded moving picture data to said transition effect processing in accordance with the received command so as to effect said transition effect processing. Other features and advantages of the present invention will be apparent from the following description 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 Fig. 1 is a block diagram illustrating an example of the configuration of a system for processing a moving picture by a moving-picture processing method according to a first embodiment of the present invention; Figs. 2A and 2B are flowcharts illustrating procedures for editing a moving picture according to the prior art; Figs. 3A and 3B are flowcharts illustrating procedures for editing a moving picture according to an embodiment of the present invention; Fig. 4 is a block diagram of an item; Fig. 5 is a block diagram of an other item; Fig. 6A is a diagram illustrating a fade-out processing according to an embodiment of the present invention; and Fig. 6B is a diagram illustrating a conventional fade-out processing. DESCRIPTION OF THE PREFERRED EMBODIMENTS Methods of processing a moving picture according to embodiments of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a block diagram illustrating an example of the configuration of a system for processing a moving picture according to an embodiment of the present invention. The system shown in Fig. 1 is composed of a plurality of terminals a1, b2, c3, ··· interconnected by a communication line 101. The terminal a1 is constructed as set forth below. Specifically, the terminal al includes an input port 11 for accepting moving-picture data from an image input unit 19 such as a video camera, and a CPU 12 for executing the processing of image data in accordance with a control program stored in a ROM 14 as well as overall control of the terminal a1 via a bus 18. Further, by accessing a prescribed area in a RAM 13, the CPU 12 is capable of reading out a pixel value at any coordinates of any frame of the moving-picture data stored in the RAM 13. The terminal a1 further includes a coding/decoding circuit 15, a display 16 and an interface 17 through which data communication is performed with the communication line 101. The aforementioned components of the terminal a1 are interconnected by a bus 18. The terminals b2, c3, ··· have substantially the same construction as that of the terminal a1. Figs. 3A and 3B are flowcharts illustrating procedures for editing a moving picture according to the first embodiment of the present invention, in which Fig. 3A shows the procedure performed by a terminal on the transmitting side and Fig. 3B the procedure performed by a terminal on the receiving side. According to the flowchart shown in Fig. 3A, the terminal on the transmitting side according to this embodiment reads moving-picture data into the RAM 13 via the input portion 11 at step S12. Next, the terminal on the transmitting side accepts a plurality of effect designations, such as a superimposing designation or a designation of the transition effect (fade out, wipe, etc.), at step S12. Next, the transmitting terminal sends effect-designating data (command data), which has been accepted at step S12, to the communication line 101 at step S13. This is followed by step S14, at which the transmitting terminal codes the moving-picture data by the coding/decoding circuit 15, and then by step S15, at which the coded data is sent to the communication line 101 via the interface 17. It should be noted that an arrangement may be adopted in which the moving-picture data is coded in advance and the effect-designating data is attached thereto before the moving-picture data is sent to the communication line 101. More specifically, in this embodiment, the effect-designating data and the coded, unedited moving-picture data are transmitted. Next, according to the flowchart shown in Fig. 3B, the terminal on the receiving side receives the effect-designating data via the interface 17 at step S16 and stores this data in the RAM 13. The receiving terminal then receives the coded data of the moving-picture data via the interface 17 at step S17 and stores this data in the RAM 13. This is followed by step S18, at which the receiving terminal decodes the coded data, which has been stored in the RAM 13, by the coding/decoding circuit 15 and then stores the moving-picture data obtained by decoding in the RAM 13. Next, at step S19, the terminal on the receiving side edits the moving-picture data, which has been stored in the RAM 13, based upon the effect-designating data stored in the RAM 13. The editing operation may be performed as follows, by way of example: Assume that the rate of the received moving-picture data is five frames per second, and that the display rate of the display 16 is 20 frames per second. If command data for performing fade-out has been received, fade-out processing is executed after performing interpolation between frames of the moving picture of five frames per second and creating moving-picture data of 20 frames per second (Fig. 6A). The simplest example of interpolation processing here is merely to repeat the same picture for four frames. Note that moving-picture data according to the conventional processing is as shown in Fig. 6B. Furthermore, besides fade-out, a transition effect such as wiping also can be carried out through a method similar to that described above. Finally, at step S20, the terminal on the receiving side displays the moving picture on the display unit 16. Thus, according to this embodiment of the invention, after the effect-designating data and moving-picture data have been received at the terminal on the receiving side, the moving-picture data obtained by decoding the coded data is edited based upon the effect-designating data. When it is attempted to superimpose characters, for example, upon a moving picture in the example of the prior art described above, the image data on which line-drawing data (i.e., a character) has been superimposed is coded. In a well-known moving-picture coding method (e.g., a coding method according to the MPEG) the main purpose of which is to compress a natural image, compression cannot be performed efficiently and, hence, there is an increase in the amount of coded data, when it is attempted to improve picture quality. On the other hand, when it is attempted to raise the compression rate, there is a marked decline in picture quality. For example, it may become difficult to read the characters. Furthermore, when fade-out of a moving picture is performed in a case where the moving-picture data is transmitted at a low frame rate of ten frames per second in the prior art, a change in the image to be faded out also is expressed at a low frame rate. As a result, a jerky, crude effect is all that is obtained. By contrast, the superimposing of characters is carried out immediately before the display of the image in the terminal on the receiving side. As a result, there is no decline in compression efficiency and no deterioration in picture quality. Further, in a case where fade-out of a moving picture is performed according to this embodiment, it is easy to make the frame rate solely of the changing portion of the image to be faded out higher than that of other portions by performing the above-described interpolation processing in the terminal on the receiving side. This makes it possible to obtain smooth fade-out without any deterioration in the transmission efficiency of the image data. In the foregoing description and in the drawings, an example is described in which coding/decoding of a moving picture is carried out by the coding/decoding circuit 15. However, the embodiment is not limited to this arrangement. For example, the coding/decoding of the moving picture may be realized by software processing executed by the CPU 12. Though processing speed will decline in such case, the cost of the terminal can be reduced. Further, in the foregoing description and in the drawings, an example is described in which moving-picture data entered by the input port 11 or coded data received by the interface 17 is stored in the RAM 13 as is. However, the embodiment is not limited to this arrangement. For example, by providing a sufficiently fast coding/decoding circuit, coding may be performed in real time while the moving-picture data is being entered or decoding may be performed in real time while coded data is being received, with the data then being stored in the RAM 13. In this case, the processing speed can be raised or, in the former case, the memory capacity of the RAM 13 can be reduced. Further, in the foregoing description and in the drawings, an example is described in which a RAM is used for the storing of data. However, the embodiment is not limited to this arrangement. For example, if high-speed processing is not required, an external storage device such a hard disk may be employed. In such case, a large quantity of moving-picture data can be processed at low cost. Thus, in accordance with the embodiment as described above, moving-picture data is edited in a terminal on the receiving side, whereby a high-quality moving-picture transmission can be realized without inviting a decline in compression efficiency or a deterioration in picture quality by coding/decoding. It should be noted that the terminal according to this embodiment may be a system composed of a plurality of devices, e.g., a system of video cameras or host computers, or an apparatus comprising a single device, e.g., a host computer in which a moving picture is stored. Further, the processing according to this embodiment may be realized by supplying a program, which has been stored on a medium, to a system or apparatus. Thus, in accordance with the embodiment of the present invention, there can be provided a moving-picture transmitting method for transmitting information for editing moving-picture data, coding the moving-picture data efficiently and then transmitting the coded data. Further, in accordance with the embodiment of the present invention, there can be provided a moving-picture transmitting method for editing moving-picture data, which has been obtained by decoding coded data that has been received, based upon the received editing information. The moving-picture processing method of the embodiment described above is applied to a technique in which text is superimposed on a picture in synchronism with a moving picture, as in the case of captions superimposed on a movie or the words to a song superimposed on a moving picture in a karaoke sing-along system. In this item, moving-picture data and text data such as captions are held separately. At playback, the text such as captions is developed into a bitmap and superimposed on the picture. As a result, it is possible to prevent a deterioration in picture quality, at the time of image compression/decompression, caused by the insertion of text such as captions. At the same time, problems of operability are solved. Fig. 4 is a block diagram showing a moving-picture processing system according to this item. The system includes a memory 111 for storing caption text data, a memory 112 for storing moving-picture data, a moving-picture compressing circuit 113, a multiplexer 114, a store-and-forward transmission system 115, a demultiplexer 116, a moving-picture decompressing circuit 117, a caption superimposer 118, a display unit 119 and signal lines 120, 121. Moving-picture data that has been accumulated in the memory 112 is compressed by the moving-picture compressing circuit 113, and this data is combined with text data, which has been accumulated in the memory 111, in the multiplexer 114. The combined data is sent from ' the multiplexer 114 to the store-and-forward transmission system 115. The store-and-forward transmission system 115, which may be packaged media such as a tape or CD-ROM or a communication system such as an ISDN or TV broadcast, is used to deliver data to the location of the user. The data accepted by the user is separated into compressed-image data and text data by the demultiplexer 116. The image data is sent to the moving-picture decompressing circuit 117 through the signal line 120. The text data is sent to the caption superimposer 118 through the signal line 121, and the superimposer 118 develops the text data into a bit-mapped text image and superimposes the bit-mapped text image on the moving picture decompressed by the moving-picture decompressing circuit 117. The thus obtained moving picture having captions is displayed by the display unit 119. It should be noted that the moving picture can be obtained as hard copies frame by frame using an image forming apparatus (such as a laser printer) instead of the display unit. Further, it is possible to print out only the captions. A noteworthy feature of this item is that caption superimposer 118 is located on the side of the user. In addition, by employing a control panel 122, the user can set display/non-display of captions, the color of the caption display and its position on the screen as well as the size of the characters. On the basis of the settings made, a control circuit 123 controls the superimposing operation by means of the caption superimposer 118. With the conventional transmission method, the caption superimposer is located on the transmitting side (the side of the producer of the moving picture), and therefore captions are always displayed at a fixed position. By contrast, in accordance with this item, the user applies commands to the caption superimposer so that it is possible to freely set display/non-display of captions, the color of the caption display and its position on the screen as well as the size of the characters. This represents a great improvement in operability. Furthermore, in accordance with this item, it is possible to provide the excellent picture quality and compression efficiency described above. Further, an MPEG encoder, which is a moving-picture compression system in accordance with international standards, can be used as the moving-picture compressing circuit 113 shown in Fig. 4. Since a "user data area" is defined in the MPEG bit stream and any data can be written in for each picture in conformity with the MPEG, the multiplexer 114 performs an operation through which the text data is written in the "user data area". The demultiplexer 116 reads out text data from the "user data area" of the MPEG bit stream and sends it to the caption superimposer 118. The moving-picture decompressing circuit 117 uses an MPEG decoder. In accordance with this item, an advantage is that it is possible to generate coded data that is in conformity with the MPEG. In a case where data is reproduced using an ordinary MPEG decoder instead of the method of reproduction described in this embodiment, the user data area is ignored so that captions simply are no longer capable of being displayed. The moving picture, however, can be still reproduced correctly. Thus, compatibility is maintained. In accordance with the item as described above, it is possible to avoid a deterioration in picture quality caused by text being superimposed on the picture. In addition, the user is capable of freely selecting the method of displaying captions. Fig. 5 is a block diagram showing a moving-picture processing system according to an other item. The system includes memories 131, 132, 133 for storing caption text data, a memory 134 for storing a moving picture, a moving-picture compressing circuit 135, a multiplexer 136, a store-and-forward transmission system 137, a demultiplexer 138, a moving-picture decompressing circuit 139, a caption superimposer 140, a display unit 141 and a changeover switch 142. The memories 131, 132, 133 contain different types of text data. For example, assume that the memories 131, 132, 133 contain captions in Japanese, English and Chinese, respectively. These three types of text data are sent to the multiplexer 136, which superimposes the data on image data obtained from the memory 134 and then compressed via the moving-picture compressing circuit 135. The resulting data is sent to the store-and-forward transmission system 137. On the receiving side, the data is passed through the demultiplexer 138 to separate it into the compressed image data and the three types of text data. The compressed image data is decompressed by the moving-picture decompressing circuit 139 and the decompressed data is then sent to the caption superimposer 140. Any one of the three types of text data is selected by the switch 142. According to this embodiment, the user is capable of selecting a caption in the desired language from among the captions in three languages. The text data selected is developed into a bitmap by the superimposer 140 and superimposed upon the moving picture, with the result being displayed on the display unit 141. By adopting the arrangement described above, the user is capable of selecting and displaying any caption of a plurality of types. Though the types of caption text are made available in three systems, it goes without saying that this does not constitute a limitation. Caption text of types in any number of systems can be entered to the extent allowed by the capacity of the store-and-forward transmission system and the transfer capability. In addition, it is not necessary to prepare text in a number of languages, and it goes without saying that text having different content in the same language can be entered as well. Instead of developing text into a bitmap and superimposing it on an image, an arrangement may be adopted in which text is read by a voice synthesizer and either mixed with audio that accompanies a moving picture or substituted for the audio before playback is performed. As many apparently widely different embodiments of the present invention can be made without departing from the scope thereof, it is to be understood that the invention is not limited to the specific embodiment thereof except as defined in the appended claims.

Claims: A moving picture processing apparatus comprising: receiving means (17) operable to receive from a transmission line encoded digital moving picture data representing a moving picture; and decoding means (15) operable to decode the encoded digital moving picture data; said receiving means (17) is adapted also to receive, from said transmission line, command data including a command for commanding transition effect processing characterised in that: said transition effect processing is to be applied to the decoded moving picture data; and in that said apparatus further comprising processing means (12) operable to subject the decoded moving picture data to said transition effect processing in accordance with the received command so as to effect said transition effect processing. Apparatus according to claim 1 further comprising interpolation means for executing frame interpolation processing on said digital moving picture data to provide processed digital moving picture data at a frame rate greater than a frame rate of the digital moving picture data received by said receiving means, wherein said processing means performs said transition effect processing after said interpolation processing. Apparatus as claimed in any preceding claim further comprising image forming means (16) for forming images using the processed decoded moving picture data received by said receiving means. Apparatus as claimed in any preceding claim wherein said transition effect processing applied a transition effect constituted by any one of a fade out effect and a wiping effect. Apparatus as claimed in any preceding claim comprising a RAM (13) storing said encoded digital moving picture data and said command data. A method of processing a moving picture comprising the steps of: receiving from a transmission line encoded digital moving picture data representing a moving picture; and decoding the encoded digital moving picture data; said receiving step is adapted to receive from said transmission line command data including a command for commanding transition effect processing characterised in that : said transition effect processing is to be applied to the decoded moving picture data; and in that the method further comprises: a processing step subjecting the decoded moving picture data to said transition effect processing in accordance with the received command so as to effect said transition effect processing. A method according to claim 6 wherein said decoding step includes an interpolating step for executing frame interpolation processing on said digital moving picture data to provide processed digital moving-picture data at a frame rate greater than a frame rate of the digital moving picture data received by said receiving step, and wherein said transition effect processing is performed after said interpolation processing. A method according to any of claims 6 and 7, wherein said transition effect processing step executes a transition effect constituted by any one of a fade out effect and a wiping effect. A method as claimed in any of claim 6 to 8 including the step of forming images using the processed decoded moving picture data.

Inventors: YAMAMOTO KUNIHIRO, YAMAMOTO, KUNIHIRO, YAMAMOTO, KUNIHIRO, CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1993
Main classification: H04N5
IPC codes: H04N5, G11B27, H04N7