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54 const uint8_t *bytestream = avpkt->
data;
55 const uint8_t *bytestream_end = bytestream + avpkt->
size;
66 for (
i = 0;
i < 16;
i++) {
67 a->delta[
i] = *bytestream++;
71 for (y = 0; y < avctx->
height; y++) {
81 for (
i = 0;
i < 4;
i++)
82 a->offset[
i] = *bytestream++;
84 offset =
a->offset[0] -
a->delta[bytestream[2] & 0xF];
85 for (x = 0; x < avctx->
width; x += 4) {
86 luma[0] =
offset +=
a->delta[bytestream[2] & 0xF];
87 luma[1] =
offset +=
a->delta[bytestream[2] >> 4];
88 luma[2] =
offset +=
a->delta[bytestream[0] & 0xF];
89 luma[3] =
offset +=
a->delta[bytestream[0] >> 4];
92 *
cb++ = bytestream[3];
93 *
cr++ = bytestream[1];
100 offset =
a->offset[y & 3] -
a->delta[bytestream[2] & 0xF];
102 for (x = 0; x < avctx->
width; x += 8) {
103 luma[0] =
offset +=
a->delta[bytestream[2] & 0xF];
104 luma[1] =
offset +=
a->delta[bytestream[2] >> 4];
105 luma[2] =
offset +=
a->delta[bytestream[3] & 0xF];
106 luma[3] =
offset +=
a->delta[bytestream[3] >> 4];
107 luma[4] =
offset +=
a->delta[bytestream[0] & 0xF];
108 luma[5] =
offset +=
a->delta[bytestream[0] >> 4];
109 luma[6] =
offset +=
a->delta[bytestream[1] & 0xF];
110 luma[7] =
offset +=
a->delta[bytestream[1] >> 4];
119 return bytestream - avpkt->
data;
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
static double cb(void *priv, double x, double y)
This structure describes decoded (raw) audio or video data.
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
AVCodec p
The public AVCodec.
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
#define FF_CODEC_DECODE_CB(func)
#define av_assert0(cond)
assert() equivalent, that is always enabled.
#define CODEC_LONG_NAME(str)
static int vcr1_decode_frame(AVCodecContext *avctx, AVFrame *p, int *got_frame, AVPacket *avpkt)
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
int(* init)(AVBSFContext *ctx)
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
const FFCodec ff_vcr1_decoder
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
#define i(width, name, range_min, range_max)
const char * name
Name of the codec implementation.
static av_cold int vcr1_decode_init(AVCodecContext *avctx)
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
main external API structure.
#define avpriv_request_sample(...)
This structure stores compressed data.
static double cr(void *priv, double x, double y)
int width
picture width / height.
int linesize[AV_NUM_DATA_POINTERS]
For video, a positive or negative value, which is typically indicating the size in bytes of each pict...
@ AV_PIX_FMT_YUV410P
planar YUV 4:1:0, 9bpp, (1 Cr & Cb sample per 4x4 Y samples)
#define AVERROR_INVALIDDATA
Invalid data found when processing input.