FFmpeg: libavcodec/yuv4dec.c Source File

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libavcodec

yuv4dec.c

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1 /*

2 * libquicktime yuv4 decoder

3 *

5 *

6 * This file is part of FFmpeg.

7 *

8 * FFmpeg is free software; you can redistribute it and/or

9 * modify it under the terms of the GNU Lesser General Public

10 * License as published by the Free Software Foundation; either

11 * version 2.1 of the License, or (at your option) any later version.

12 *

13 * FFmpeg is distributed in the hope that it will be useful,

14 * but WITHOUT ANY WARRANTY; without even the implied warranty of

15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

16 * Lesser General Public License for more details.

17 *

18 * You should have received a copy of the GNU Lesser General Public

19 * License along with FFmpeg; if not, write to the Free Software

20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

21 */

23 #include "avcodec.h"

24 #include "codec_internal.h"

25 #include "internal.h"

27 static av_cold int yuv4_decode_init(AVCodecContext *avctx)

28 {

29 avctx->pix_fmt = AV_PIX_FMT_YUV420P;

31 return 0;

32 }

34 static int yuv4_decode_frame(AVCodecContext *avctx, AVFrame *pic,

35 int *got_frame, AVPacket *avpkt)

36 {

37 const uint8_t *src = avpkt->data;

38 uint8_t *y, *u, *v;

39 int i, j, ret;

41 if (avpkt->size < 6 * (avctx->width + 1 >> 1) * (avctx->height + 1 >> 1)) {

42 av_log(avctx, AV_LOG_ERROR, "Insufficient input data.\n");

43 return AVERROR(EINVAL);

44 }

46 if ((ret = ff_get_buffer(avctx, pic, 0)) < 0)

47 return ret;

49 pic->key_frame = 1;

50 pic->pict_type = AV_PICTURE_TYPE_I;

52 y = pic->data[0];

53 u = pic->data[1];

54 v = pic->data[2];

56 for (i = 0; i < (avctx->height + 1) >> 1; i++) {

57 for (j = 0; j < (avctx->width + 1) >> 1; j++) {

58 u[j] = *src++ ^ 0x80;

59 v[j] = *src++ ^ 0x80;

60 y[ 2 * j ] = *src++;

61 y[ 2 * j + 1] = *src++;

62 y[pic->linesize[0] + 2 * j ] = *src++;

63 y[pic->linesize[0] + 2 * j + 1] = *src++;

64 }

66 y += 2 * pic->linesize[0];

67 u += pic->linesize[1];

68 v += pic->linesize[2];

69 }

71 *got_frame = 1;

73 return avpkt->size;

74 }

76 const FFCodec ff_yuv4_decoder = {

77 .p.name = "yuv4",

78 .p.long_name = NULL_IF_CONFIG_SMALL("Uncompressed packed 4:2:0"),

79 .p.type = AVMEDIA_TYPE_VIDEO,

80 .p.id = AV_CODEC_ID_YUV4,

81 .init = yuv4_decode_init,

82 FF_CODEC_DECODE_CB(yuv4_decode_frame),

83 .p.capabilities = AV_CODEC_CAP_DR1,

84 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,

85 };

AVERROR

Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions

#define u(width, name, range_min, range_max)

Definition: cbs_h2645.c:262

AVFrame

This structure describes decoded (raw) audio or video data.

Definition: frame.h:325

ff_yuv4_decoder

const FFCodec ff_yuv4_decoder

Definition: yuv4dec.c:76

internal.h

AVPacket::data

uint8_t * data

Definition: packet.h:374