Function mpeg1_encode_picture_header

libavcodec/mpeg12enc.c:340–495

}

static int mpeg1_encode_picture_header(MPVMainEncContext *const m)
{
    MPEG12EncContext *const mpeg12 = (MPEG12EncContext*)m;
    MPVEncContext *const s = &m->s;
    const AVFrameSideData *side_data;

    put_bits_assume_flushed(&s->pb);

    mpeg1_encode_sequence_header(mpeg12);

    /* MPEG-1 picture header */
    put_header(s, PICTURE_START_CODE);
    /* temporal reference */

    put_bits(&s->pb, 10,
             (s->picture_number - mpeg12->gop_picture_number) & 0x3ff);
    put_bits(&s->pb, 3, s->c.pict_type);

    m->vbv_delay_pos = put_bytes_count(&s->pb, 0);
    put_bits(&s->pb, 16, 0xFFFF);               /* vbv_delay */

    // RAL: Forward f_code also needed for B-frames
    if (s->c.pict_type == AV_PICTURE_TYPE_P ||
        s->c.pict_type == AV_PICTURE_TYPE_B) {
        put_bits(&s->pb, 1, 0);                 /* half pel coordinates */
        if (s->c.codec_id == AV_CODEC_ID_MPEG1VIDEO)
            put_bits(&s->pb, 3, s->f_code);     /* forward_f_code */
        else
            put_bits(&s->pb, 3, 7);             /* forward_f_code */
    }

    // RAL: Backward f_code necessary for B-frames
    if (s->c.pict_type == AV_PICTURE_TYPE_B) {
        put_bits(&s->pb, 1, 0);                 /* half pel coordinates */
        if (s->c.codec_id == AV_CODEC_ID_MPEG1VIDEO)
            put_bits(&s->pb, 3, s->b_code);     /* backward_f_code */
        else
            put_bits(&s->pb, 3, 7);             /* backward_f_code */
    }

    put_bits(&s->pb, 1, 0);                     /* extra bit picture */

    s->c.frame_pred_frame_dct = 1;
    if (s->c.codec_id == AV_CODEC_ID_MPEG2VIDEO) {
        put_header(s, EXT_START_CODE);
        put_bits(&s->pb, 4, 8);                 /* pic ext */
        if (s->c.pict_type == AV_PICTURE_TYPE_P ||
            s->c.pict_type == AV_PICTURE_TYPE_B) {
            put_bits(&s->pb, 4, s->f_code);
            put_bits(&s->pb, 4, s->f_code);
        } else {
            put_bits(&s->pb, 8, 255);
        }
        if (s->c.pict_type == AV_PICTURE_TYPE_B) {
            put_bits(&s->pb, 4, s->b_code);
            put_bits(&s->pb, 4, s->b_code);
        } else {
            put_bits(&s->pb, 8, 255);