diff options
Diffstat (limited to 'vid-scratch/nutgen-gif.c')
| -rw-r--r-- | vid-scratch/nutgen-gif.c | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/vid-scratch/nutgen-gif.c b/vid-scratch/nutgen-gif.c new file mode 100644 index 0000000..15c3b75 --- /dev/null +++ b/vid-scratch/nutgen-gif.c @@ -0,0 +1,289 @@ +/* nut.c - A simple NUT encoder with the following properties: + * + * - Each frame is an uncompressed 8-bit RGB (specifically `(msb)2B + * 3G 3R(lsb)`, known as the 4CC "BGR\x08") framebuffer. + * + * - Each pixel in the framebuffer is non-square; it is twice as tall + * as it is wide. + * + * - The display-resolution of each frame may change between 640x480, + * 720x480, and 720x576. This is the display-resolution; because + * of non-square pixels, the framebuffer for each would be 640x240, + * 720x240, and 720x288, respectively. + * + * - VFR (Variable Frame Rate) - Each frame has its own timestamp. + */ + +#include <fcntl.h> /* for open() */ + +#include "common.h" + +/* High-level (specific to the properties we want) ****************************/ + +enum app_res { + APP_RES_INVALID = -1, + APP_RES_640_480 = 0, + APP_RES_720_480 = 1, + APP_RES_720_576 = 2, + APP_RES_NUM = 3, +}; +#define APP_RES_MIN APP_RES_640_480 +#define APP_RES_MAX APP_RES_720_576 + +size_t app_res_w(enum app_res res) { + switch (res) { + case APP_RES_640_480: return 640; + case APP_RES_720_480: return 720; + case APP_RES_720_576: return 720; + default: assert_notreached("invalid res"); + } +} +size_t app_res_h(enum app_res res) { + switch (res) { + case APP_RES_640_480: return 480/2; + case APP_RES_720_480: return 480/2; + case APP_RES_720_576: return 576/2; + default: assert_notreached("invalid res"); + } +} +size_t app_res_fb_size(enum app_res res) { + return app_res_w(res)*app_res_h(res); +} + +#define APP_FRAME_SIZE_MSB_MUL 0x2000 /* must be less than 0x4000 */ +#define APP_FRAME_MAX_HEADER 16 + +struct app_state { + enum app_res res; + uint64_t len; + uint64_t last_syncpoint; +}; + +#define GIF_SCREENFLAG_GLOBAL_COLOR_TABLE (1<<7) +#define GIF_SCREENFLAG_BITS_PER_COLOR(x) ({ static_assert((x) <= 8); (((x)-1)&0b111)<<4; }) +#define GIF_SCREENFLAG_GLOBAL_COLOR_TABLE_SORTED (1<<3) +#define GIF_SCREENFLAG_GLOBAL_COLOR_TABLE_SIZE(x) ({ static_assert(__builtin_popcount(x) == 1 && __builtin_ctz(x) <= 8); __builtin_ctz(x)-1; }) + +#define GIF_ASPECT_RATIO(w, h) (64*(w)/(h)+15) + +#define GIF_IMAGEFLAG_LOCAL_COLOR_TABLE (1<<7) +#define GIF_IMAGEFLAG_INTERLACE (1<<6) +#define GIF_IMAGEFLAG_LOCAL_COLOR_TABLE_SORTED (1<<5) +#define _GIF_IMAGEFLAG_4 (1<<4) +#define _GIF_IMAGEFLAG_3 (1<<3) +#define GIF_IMAGEFLAG_LOCAL_COLOR_TABLE_SIZE(x) ({ static_assert(__builtin_popcount(x) == 1 && __builtin_ctz(x) <= 8); __builtin_ctz(x)-1; }) + +#define UINT16LE(x) ((x)&0xFF), (((x)>>8)&0xFF) + +void app_append_intro(struct buf *out, enum app_res res) { + [[maybe_unused]] uint8_t intro[] = { + /* Header */ + 'G', 'I', 'F', /*! Signature */ + '8', '9', 'a', /*! Version */ + + /* Logical Screen Descriptor */ + UINT16LE(app_res_w(res)), /*! Logical Screen Width */ + UINT16LE(app_res_h(res)), /*! Logical Screen Height */ + GIF_SCREENFLAG_GLOBAL_COLOR_TABLE| /*! Global Color Table Flag */ + GIF_SCREENFLAG_BITS_PER_COLOR(8)| /*! Color Resolution */ + 0| /*! Sort Flag */ + GIF_SCREENFLAG_GLOBAL_COLOR_TABLE_SIZE(256), /*! Size of Global Color Table */ + 0, /*! Background Color Index */ + GIF_ASPECT_RATIO(1, 2), /*! Pixel Aspect Ratio */ + + /* Global Color Table */ + /* identity-map R:G:B 3:3:2 bits */ +#define R3(idx) (((idx)>>5)&0b111) +#define G3(idx) (((idx)>>2)&0b111) +#define B2(idx) (((idx)>>0)&0b011) +#define R8(idx) ( (R3(idx)<<5) | (R3(idx)<<2) | (R3(idx)>>1) ) +#define G8(idx) ( (G3(idx)<<5) | (G3(idx)<<2) | (G3(idx)>>1) ) +#define B8(idx) ( (B2(idx)<<6) | (B2(idx)<<4) | (B2(idx)<<2) | (B2(idx)<<0) ) +#define COLOR(idx) R8(idx), G8(idx), B8(idx) +#define COLOR_2(base_idx) COLOR (base_idx), COLOR (base_idx+ 1) +#define COLOR_4(base_idx) COLOR_2 (base_idx), COLOR_2 (base_idx+ 2) +#define COLOR_8(base_idx) COLOR_4 (base_idx), COLOR_4 (base_idx+ 4) +#define COLOR_16(base_idx) COLOR_8 (base_idx), COLOR_8 (base_idx+ 8) +#define COLOR_32(base_idx) COLOR_16 (base_idx), COLOR_16 (base_idx+ 16) +#define COLOR_64(base_idx) COLOR_32 (base_idx), COLOR_32 (base_idx+ 32) +#define COLOR_128(base_idx) COLOR_64 (base_idx), COLOR_64 (base_idx+ 64) +#define COLOR_256(base_idx) COLOR_128(base_idx), COLOR_128(base_idx+128) + COLOR_256(0), + + /* Image Descriptor */ + 0x2C, /*! Image Separator */ + UINT16LE(0), /*! Image Left Position */ + UINT16LE(0), /*! Image Top Position */ + UINT16LE(app_res_w(res)), /*! Image Width */ + UINT16LE(app_res_h(res)), /*! Image Height */ + 0| /*! Local Color Table Flag */ + 0, /*! Interlace Flag */ + + + }; + struct buf pkt = {0}; + unsigned int frame_code = 0; +#define INC_FRAME_CODE() do { frame_code++; if (frame_code == 'N') frame_code++; } while(0) + + append(out, nut_file_id_string, sizeof(nut_file_id_string)); + +#define BOGUS(n) n + /* main_header ********************************************************/ + pkt.len = 0; + + /* head *******************************************/ + nut_append_vu(&pkt, 3); /*! version */ + nut_append_vu(&pkt, 1); /*! stream_count */ + nut_append_vu(&pkt, /*! max_distance */ + APP_FRAME_MAX_HEADER + + app_res_fb_size(res)); + + /* time bases *************************************/ + nut_append_vu(&pkt, 1); /*! time_base_count */ + + /* time_base[0] = 1ns */ + nut_append_vu(&pkt, 1); /*! numerator */ + nut_append_vu(&pkt, 1000000000ULL); /*! denominator */ + + /* frame codes ************************************/ + /* "A muxer SHOULD mark [frame codes] 0x00 and 0xFF as invalid" */ + + /* frame_code=0 (invalid) */ + nut_append_vu(&pkt, NUT_FRAMEFLAG_INVALID); /*! flags */ + nut_append_vu(&pkt, 2); /*! field_count */ + nut_append_vu(&pkt, BOGUS(0)); /*! 0: fields.pts */ + nut_append_vu(&pkt, 1); /*! 1: fields.size_msb_nul */ + INC_FRAME_CODE(); + + /* frame_code=1 (res) */ + nut_append_vu(&pkt, /*! flags */ + NUT_FRAMEFLAG_KEY | /* Because they're full framebuffers, all frames are keyframes. */ + NUT_FRAMEFLAG_SIZE_MSB | /* 640*480/2 > 16384 (the max val of data_size_lsb). */ + NUT_FRAMEFLAG_CODED_PTS | /* framerate is unknown, each frame must have a timestamp. */ + NUT_FRAMEFLAG_CHECKSUM ); /* framerate is unknown, guard against exceeding max_pts_distance. */ + nut_append_vu(&pkt, 6); /*! field_count */ + nut_append_vu(&pkt, BOGUS(0)); /*! 0: fields.pts */ + nut_append_vu(&pkt, APP_FRAME_SIZE_MSB_MUL); /*! 1: fields.size_msb_nul */ + nut_append_vu(&pkt, 0); /*! 2: fields.stream */ + nut_append_vu(&pkt, /*! 3: fields.size_lsb */ + app_res_fb_size(res) % APP_FRAME_SIZE_MSB_MUL); + nut_append_vu(&pkt, 0); /*! 4: fields.reserved */ + nut_append_vu(&pkt, 1); /*! 5: fields.count */ + INC_FRAME_CODE(); + + /* frame_code=N-255 (invalid) */ + nut_append_vu(&pkt, NUT_FRAMEFLAG_INVALID); /*! flags */ + nut_append_vu(&pkt, 2); /*! field_count */ + nut_append_vu(&pkt, BOGUS(0)); /*! 0: fields.pts */ + nut_append_vu(&pkt, /*! 1: fields.size_msb_nul */ + 256-frame_code-(frame_code < 'N' ? 1 : 0)); + + /* tail *******************************************/ + nut_append_vu(&pkt, 0); /*! header_count_minus_1 */ + + nut_append_packet(out, nut_startcode_main, pkt.dat, pkt.len); + + /* stream_header ******************************************************/ + pkt.len = 0; + + nut_append_vu(&pkt, 0); /*! stream_id */ + nut_append_vu(&pkt, NUT_STREAMCLASS_VIDEO); /*! stream_class */ + nut_append_vb(&pkt, "BGR\x08", 4); /*! fourcc */ + nut_append_vu(&pkt, 0); /*! time_base_id */ + nut_append_vu(&pkt, 0); /*! msb_pts_shift */ + nut_append_vu(&pkt, BOGUS(0)); /*! max_pts_distance (all frames have a checksum) */ + nut_append_vu(&pkt, 0); /*! decode_delay */ + nut_append_vu(&pkt, 0); /*! stream_flags */ + nut_append_vb(&pkt, NULL, 0); /*! codec_specific_data */ + nut_append_vu(&pkt, app_res_w(res)); /*! width */ + nut_append_vu(&pkt, app_res_h(res)); /*! height */ + nut_append_vu(&pkt, 1); /*! sample_width */ + nut_append_vu(&pkt, 2); /*! sample_height */ + nut_append_vu(&pkt, NUT_COLORSPACE_UNKNOWN); /*! colorspace_type */ + + nut_append_packet(out, nut_startcode_stream, pkt.dat, pkt.len); + + /* flush **************************************************************/ +#undef BOGUS + + free(pkt.dat); +} + +bool app_write_frame(int fd, struct app_state *state, uint64_t time_ns, enum app_res res, void *framebuffer) { + assert(framebuffer); + assert(0 <= res && res < APP_RES_NUM); + + struct buf out = {0}; + struct buf pkt = {0}; + + if (res != state->res) { + app_append_intro(&out, res); + state->res = res; + } + + /* syncpoint packet ***************************************************/ + pkt.len = 0; + uint64_t syncpoint_beg = state->len + out.len; + + nut_append_vu(&pkt, time_ns); /*! global_key_pts */ + nut_append_vu(&pkt, state->last_syncpoint /*! back_ptr_div16 */ + ? (syncpoint_beg - state->last_syncpoint)/16 + : 0); + + nut_append_packet(&out, nut_startcode_syncpoint, pkt.dat, pkt.len); + + /* frame header ( 1+10+1+4 = 16 bytes) */ + uint64_t frame_beg = out.len; + nut_append_u8(&out, 1); /*! frame_code (1 byte) */ + nut_append_vu(&out, time_ns); /*! coded_pts (<=10 bytes) */ + nut_append_vu(&out, app_res_fb_size(res) / APP_FRAME_SIZE_MSB_MUL); /*! data_size_msb (1 byte) */ + nut_append_u32(&out, nut_crc32(&out.dat[frame_beg], out.len - frame_beg)); /*! checksum (4 bytes) */ + assert(out.len - frame_beg <= APP_FRAME_MAX_HEADER); + + /* flush */ + bool err = xwrite(fd, out.dat, out.len); + free(out.dat); + free(pkt.dat); + if (err) + return true; + + /* frame data */ + if (xwrite(fd, framebuffer, app_res_fb_size(res))) + return true; + + /* return */ + state->res = res; + state->len += out.len + app_res_fb_size(res); + state->last_syncpoint = syncpoint_beg; + return false; +} + +/* Demo application ***********************************************************/ + +int main() { + struct app_state state = { + .res = APP_RES_INVALID, + }; + + uint8_t framebuffer[app_res_fb_size(APP_RES_MAX)]; + +#define SCALE 10 + for (int i = 0; i < 10; i++) { + enum app_res res = (i/2)%APP_RES_NUM; + memset(framebuffer, 0b00011000, sizeof(framebuffer)); + for (int y = 0; y < 4*SCALE; y++) + for (int x = 0; x < 8*SCALE; x++) + framebuffer[(y*app_res_w(res))+x] = font[i][((y/SCALE)*8)+(x/SCALE)] == ' ' ? 0b11000000 : 0b00000011; + if (i%2 == 0) { + char name[] = {'o', 'u', 't', '-', '0'+(i/2), '.', 'g', 'i', 'f', '\0'}; + int fd = open(name, O_WRONLY|O_TRUNC|O_CREAT, 0666); + dup2(fd, 1); + close(fd); + state.len = 0; + state.last_syncpoint = 0; + } + if (app_write_frame(1, &state, ((uint64_t)i)*1000000000ULL, res, framebuffer)) + return 1; + } + return 0; +} |