Function jpeg_create_header

libavformat/rtpdec_jpeg.c:94–190

}

static int jpeg_create_header(uint8_t *buf, int size, uint32_t type, uint32_t w,
                              uint32_t h, const uint8_t *qtable, int nb_qtable,
                              int dri)
{
    PutByteContext pbc;
    uint8_t *dht_size_ptr;
    int dht_size, i;

    bytestream2_init_writer(&pbc, buf, size);

    /* Convert from blocks to pixels. */
    w <<= 3;
    h <<= 3;

    /* SOI */
    jpeg_put_marker(&pbc, SOI);

    /* JFIF header */
    jpeg_put_marker(&pbc, APP0);
    bytestream2_put_be16(&pbc, 16);
    bytestream2_put_buffer(&pbc, "JFIF", 5);
    bytestream2_put_be16(&pbc, 0x0102);
    bytestream2_put_byte(&pbc, 0);
    bytestream2_put_be16(&pbc, 1);
    bytestream2_put_be16(&pbc, 1);
    bytestream2_put_byte(&pbc, 0);
    bytestream2_put_byte(&pbc, 0);

    if (dri) {
        jpeg_put_marker(&pbc, DRI);
        bytestream2_put_be16(&pbc, 4);
        bytestream2_put_be16(&pbc, dri);
    }

    /* DQT */
    jpeg_put_marker(&pbc, DQT);
    bytestream2_put_be16(&pbc, 2 + nb_qtable * (1 + 64));

    for (i = 0; i < nb_qtable; i++) {
        bytestream2_put_byte(&pbc, i);

        /* Each table is an array of 64 values given in zig-zag
         * order, identical to the format used in a JFIF DQT
         * marker segment. */
        bytestream2_put_buffer(&pbc, qtable + 64 * i, 64);
    }

    /* DHT */
    jpeg_put_marker(&pbc, DHT);
    dht_size_ptr = pbc.buffer;
    bytestream2_put_be16(&pbc, 0);

    dht_size  = 2;
    dht_size += jpeg_create_huffman_table(&pbc, 0, 0,ff_mjpeg_bits_dc_luminance,
                                          ff_mjpeg_val_dc);
    dht_size += jpeg_create_huffman_table(&pbc, 0, 1, ff_mjpeg_bits_dc_chrominance,
                                          ff_mjpeg_val_dc);
    dht_size += jpeg_create_huffman_table(&pbc, 1, 0, ff_mjpeg_bits_ac_luminance,