JP6011641B2 - Encoder - Google Patents

Description

  The present invention relates to an encoding apparatus capable of performing repeat processing according to the usage rate of an encoder buffer.

  In the encoding apparatus, the input original image is temporarily stored in the video buffer, and then input to the video encoding unit, encoded, and stored in the encoder buffer. However, in the case of a difficult video at a low bit rate, there has been a problem that the encoding amount cannot be suppressed and the encoder buffer is broken down, thereby stopping the operation of the encoding device.

  On the other hand, a technique has been proposed in which a repeat signal is generated when the number of input frames to the video buffer is smaller than the number of output frames, and the same frame is repeatedly encoded (see, for example, Patent Document 1). In this technique, a frame that is one frame earlier than a frame that is selected when no repeat signal is generated is selected, and the selected frame or the frame immediately before it is repeatedly encoded. Then, encoding is performed by adaptively switching the frame to be encoded according to the encoding type of the encoded frame after the timing at which the repeat signal is generated.

JP 2002-34040 A

  However, the conventional technique only looks at the state of the video buffer, and cannot perform repeat processing according to the usage rate of the encoder buffer. In addition, the repeat processing method is limited to one.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an encoding apparatus capable of performing repeat processing according to the usage rate of an encoder buffer.

An encoding apparatus according to the present invention includes a video buffer that stores an input video signal, an encoding unit that encodes the video signal read from the video buffer, and a video output from the encoding unit. An encoder buffer for storing a stream, and a repeat processing method in which an I picture or a P picture in the upper field of the video signal is repeatedly read from the video buffer and encoded by the encoding unit according to the usage rate of the encoder buffer And a switching control unit.

  According to the present invention, it is possible to perform repeat processing according to the usage rate of the encoder buffer. As a result, the image quality of the entire video is improved by allocating the code amount reduced by repetition to other video.

It is a block diagram which shows the encoding apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the system of the conventional general process. It is a figure which shows the 1st system of a repeat process. It is a figure which shows the 2nd system of repeat processing.

  FIG. 1 is a block diagram showing an encoding apparatus according to Embodiment 1 of the present invention. A video signal having a pair of an upper field (Top Field) and a lower field (Bottom Field) is sequentially input from the outside. The video buffer 1 stores the input video signal. The encoding unit 2 encodes the video signal read from the video buffer 1. The encoder buffer 3 temporarily stores the video stream output from the encoding unit 2 and then outputs it.

  The control unit 4 repeatedly supplies the video buffer 1 with the same read address as that of the immediately preceding field in accordance with the usage rate of the encoder buffer 3 or an external mode forced instruction. As a result, the control unit 4 determines the repeat processing method in which the same field of the video signal is repeatedly read from the video buffer 1 and encoded by the encoding unit 2 in accordance with the usage rate of the encoder buffer 3 or the mode forcing instruction from the outside. To switch.

  FIG. 2 is a diagram showing a conventional general processing method. When the usage rate of the encoder buffer 3 is less than 80%, the fields are read from the video buffer 1 in the order in which they are stored. Note that when the code amount is reduced in the conventional method, the video amount deteriorates mainly because the code amount is suppressed by increasing the QP value or the like.

  In encoding, the P picture in the lower field immediately after the I picture in the upper field refers only to the I picture (T2). Other P pictures refer to two fields of the immediately preceding I picture or P picture. For example, the P picture (B5) refers to two P pictures (T5, B2). The B picture refers to the four fields of the immediately preceding I picture or P picture and the preceding I picture or P picture. For example, the B picture (B6) refers to four P pictures (T5, B5, T8, B8).

  FIG. 3 is a diagram illustrating a first method of repeat processing. When the usage rate of the encoder buffer 3 is 80% or more and less than 90%, the control unit 4 reads the upper field of the video signal once from the video buffer 1 and reduces the code amount by the encoding unit 2. Encode. Since the lower field that was scheduled to be read at that time is discarded, the number of pictures does not increase. For example, T2 is repeatedly read and B2 is discarded without being read.

  In encoding, since the P picture (T2) in the lower field immediately after the I picture is the same video as the I picture (T2) to be referenced, the amount of codes can be reduced. Further, since the P picture (T5) of the lower field is the same video as the P picture (T5) of the upper field to be referred to, the code amount can be reduced.

  Since the B picture cannot refer to other B pictures, there is no point in making the same picture as the B picture in the upper field. Therefore, it is necessary to prevent the picture type for repeating video from being a B picture.

  Thus, the code amount can be reduced by repeatedly reading and encoding the same field of the video signal. Since the increase in the QP value and the like due to the code amount control can be suppressed as compared with the conventional method, the deterioration of the video can be avoided.

  FIG. 4 is a diagram illustrating a second method of repeat processing. When the usage rate of the encoder buffer 3 is 90% or more, the control unit 4 reads out the upper field of the video signal from the video buffer 1 by repeating it three times or more odd times and causes the encoding unit 2 to encode it. For example, T2 is read three times, and B2, T3, and B3 are discarded without being read.

  Similarly to the first method, the P picture (T2) in the lower field immediately after the I picture is the same video as the I picture (T2) to be referred to, and therefore the code amount can be reduced. Further, since the P picture (T5) of the lower field is the same video as the P picture (T5) of the upper field to be referred to, the code amount can be reduced.

  The B picture refers to the four fields of the immediately preceding I picture or P picture and the preceding I picture or P picture. Therefore, the code amount can be reduced if any of the four fields is the same video.

  In this way, by encoding the upper field of the video signal by repeating the odd number of times three or more times, the code amount can be reduced as compared with the first method. And since the increase of QP value etc. by code amount control can be suppressed compared with the conventional system, degradation of a video can be avoided.

  In the second method, the maximum number of repetitions depends on the video buffer amount. Further, the number of repetitions can be increased as the usage rate increases, such as 3 times less than 95% and 5 times more than 95%.

  As described above, in the present embodiment, it is possible to perform repeat processing according to the usage rate of the encoder buffer. Although the use of the same field increases in the order of the first and second methods, it is possible to reduce the usage rate of the encoder buffer and prevent image distortion.

1 video buffer, 2 encoding unit, 3 encoder buffer, 4 control unit

Claims (2)

A video buffer for storing the input video signal;
An encoding unit for encoding the video signal read from the video buffer;
An encoder buffer for storing the video stream output from the encoding unit;
A control unit that switches a repeat processing method in which an I picture or a P picture of an upper field of the video signal is repeatedly read from the video buffer and encoded by the encoding unit according to a usage rate of the encoder buffer. A characteristic encoding apparatus. When the usage rate of the encoder buffer is greater than or equal to a first threshold value and less than a second threshold value, the control unit repeatedly reads the I picture or P picture of the upper field of the video signal once from the video buffer and reads the code Encoding by the encoding unit,
When the usage rate of the encoder buffer is equal to or greater than the second threshold, the control unit reads out the I-picture or P-picture of the upper field of the video signal from the video buffer by repeating the odd-numbered times of three or more times from the video buffer. The encoding device according to claim 1, wherein the encoding is performed by a unit.

Images