【FFmpeg程式設計進階】（15）FLV 編碼器Codec初始化 ff_mpv_encode_init() 程式碼分析 -- 待更新

在前面分析《【FFmpeg程式設計進階】（11）avcodec_open2() 函式程式碼分析 - 開啟Codec解碼器》時，
我們涉及到了Codec 編碼器初始化，由於程式碼比較長，我們再分一章來分析。

主要目的，還是以 FLV 編碼器為例 ，來看下編碼器初始化主要做了啥

先記錄下TODO LIST，後面再更新。

# libavcodec\flvenc.c
AVCodec ff_flv_encoder = {
    .name           = "flv",
    .long_name      = NULL_IF_CONFIG_SMALL("FLV / Sorenson Spark / Sorenson H.263 (Flash Video)"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_FLV1,
    .priv_data_size = sizeof(MpegEncContext),
    .init           = ff_mpv_encode_init,
    .encode2        = ff_mpv_encode_picture,
    .close          = ff_mpv_encode_end,
    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
    .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_YUV420P,
                                                     AV_PIX_FMT_NONE},
    .priv_class     = &flv_class,
};

一、ff_mpv_encode_init()

# libavcodec\mpegvideo_enc.c
/* init video encoder */
av_cold int ff_mpv_encode_init(AVCodecContext *avctx)
{
    MpegEncContext *s = avctx->priv_data;
    AVCPBProperties *cpb_props;
    int i, ret, format_supported;

    mpv_encode_defaults(s);

    switch (avctx->codec_id) {
    case AV_CODEC_ID_MPEG2VIDEO:
        if (avctx->pix_fmt != AV_PIX_FMT_YUV420P &&
            avctx->pix_fmt != AV_PIX_FMT_YUV422P) {
            av_log(avctx, AV_LOG_ERROR,
                   "only YUV420 and YUV422 are supported\n");
            return AVERROR(EINVAL);
        }
        break;
    case AV_CODEC_ID_MJPEG:
    case AV_CODEC_ID_AMV:
        format_supported = 0;
        /* JPEG color space */
        if (avctx->pix_fmt == AV_PIX_FMT_YUVJ420P ||
            avctx->pix_fmt == AV_PIX_FMT_YUVJ422P ||
            avctx->pix_fmt == AV_PIX_FMT_YUVJ444P ||
            (avctx->color_range == AVCOL_RANGE_JPEG &&
             (avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
              avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
              avctx->pix_fmt == AV_PIX_FMT_YUV444P)))
            format_supported = 1;
        /* MPEG color space */
        else if (avctx->strict_std_compliance <= FF_COMPLIANCE_UNOFFICIAL &&
                 (avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
                  avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
                  avctx->pix_fmt == AV_PIX_FMT_YUV444P))
            format_supported = 1;

        if (!format_supported) {
            av_log(avctx, AV_LOG_ERROR, "colorspace not supported in jpeg\n");
            return AVERROR(EINVAL);
        }
        break;
    default:
        if (avctx->pix_fmt != AV_PIX_FMT_YUV420P) {
            av_log(avctx, AV_LOG_ERROR, "only YUV420 is supported\n");
            return AVERROR(EINVAL);
        }
    }

    switch (avctx->pix_fmt) {
    case AV_PIX_FMT_YUVJ444P:
    case AV_PIX_FMT_YUV444P:
        s->chroma_format = CHROMA_444;
        break;
    case AV_PIX_FMT_YUVJ422P:
    case AV_PIX_FMT_YUV422P:
        s->chroma_format = CHROMA_422;
        break;
    case AV_PIX_FMT_YUVJ420P:
    case AV_PIX_FMT_YUV420P:
    default:
        s->chroma_format = CHROMA_420;
        break;
    }

    avctx->bits_per_raw_sample = av_clip(avctx->bits_per_raw_sample, 0, 8);

#if FF_API_PRIVATE_OPT
FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->rtp_payload_size)
        s->rtp_payload_size = avctx->rtp_payload_size;
    if (avctx->me_penalty_compensation)
        s->me_penalty_compensation = avctx->me_penalty_compensation;
    if (avctx->pre_me)
        s->me_pre = avctx->pre_me;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

    s->bit_rate = avctx->bit_rate;
    s->width    = avctx->width;
    s->height   = avctx->height;
    if (avctx->gop_size > 600 &&
        avctx->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL) {
        av_log(avctx, AV_LOG_WARNING,
               "keyframe interval too large!, reducing it from %d to %d\n",
               avctx->gop_size, 600);
        avctx->gop_size = 600;
    }
    s->gop_size     = avctx->gop_size;
    s->avctx        = avctx;
    if (avctx->max_b_frames > MAX_B_FRAMES) {
        av_log(avctx, AV_LOG_ERROR, "Too many B-frames requested, maximum "
               "is %d.\n", MAX_B_FRAMES);
        avctx->max_b_frames = MAX_B_FRAMES;
    }
    s->max_b_frames = avctx->max_b_frames;
    s->codec_id     = avctx->codec->id;
    s->strict_std_compliance = avctx->strict_std_compliance;
    s->quarter_sample     = (avctx->flags & AV_CODEC_FLAG_QPEL) != 0;
    s->rtp_mode           = !!s->rtp_payload_size;
    s->intra_dc_precision = avctx->intra_dc_precision;

    // workaround some differences between how applications specify dc precision
    if (s->intra_dc_precision < 0) {
        s->intra_dc_precision += 8;
    } else if (s->intra_dc_precision >= 8)
        s->intra_dc_precision -= 8;

    if (s->intra_dc_precision < 0) {
        av_log(avctx, AV_LOG_ERROR,
                "intra dc precision must be positive, note some applications use"
                " 0 and some 8 as base meaning 8bit, the value must not be smaller than that\n");
        return AVERROR(EINVAL);
    }

    if (avctx->codec_id == AV_CODEC_ID_AMV || (avctx->active_thread_type & FF_THREAD_SLICE))
        s->huffman = 0;

    if (s->intra_dc_precision > (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO ? 3 : 0)) {
        av_log(avctx, AV_LOG_ERROR, "intra dc precision too large\n");
        return AVERROR(EINVAL);
    }
    s->user_specified_pts = AV_NOPTS_VALUE;

    if (s->gop_size <= 1) {
        s->intra_only = 1;
        s->gop_size   = 12;
    } else {
        s->intra_only = 0;
    }

    /* Fixed QSCALE */
    s->fixed_qscale = !!(avctx->flags & AV_CODEC_FLAG_QSCALE);

    s->adaptive_quant = (avctx->lumi_masking ||
                         avctx->dark_masking ||
                         avctx->temporal_cplx_masking ||
                         avctx->spatial_cplx_masking  ||
                         avctx->p_masking      ||
                         s->border_masking ||
                         (s->mpv_flags & FF_MPV_FLAG_QP_RD)) &&
                        !s->fixed_qscale;

    s->loop_filter = !!(avctx->flags & AV_CODEC_FLAG_LOOP_FILTER);

    if (avctx->rc_max_rate && !avctx->rc_buffer_size) {
        switch(avctx->codec_id) {
        case AV_CODEC_ID_MPEG1VIDEO:
        case AV_CODEC_ID_MPEG2VIDEO:
            avctx->rc_buffer_size = FFMAX(avctx->rc_max_rate, 15000000) * 112LL / 15000000 * 16384;
            break;
        case AV_CODEC_ID_MPEG4:
        case AV_CODEC_ID_MSMPEG4V1:
        case AV_CODEC_ID_MSMPEG4V2:
        case AV_CODEC_ID_MSMPEG4V3:
            if       (avctx->rc_max_rate >= 15000000) {
                avctx->rc_buffer_size = 320 + (avctx->rc_max_rate - 15000000LL) * (760-320) / (38400000 - 15000000);
            } else if(avctx->rc_max_rate >=  2000000) {
                avctx->rc_buffer_size =  80 + (avctx->rc_max_rate -  2000000LL) * (320- 80) / (15000000 -  2000000);
            } else if(avctx->rc_max_rate >=   384000) {
                avctx->rc_buffer_size =  40 + (avctx->rc_max_rate -   384000LL) * ( 80- 40) / ( 2000000 -   384000);
            } else
                avctx->rc_buffer_size = 40;
            avctx->rc_buffer_size *= 16384;
            break;
        }
        if (avctx->rc_buffer_size) {
            av_log(avctx, AV_LOG_INFO, "Automatically choosing VBV buffer size of %d kbyte\n", avctx->rc_buffer_size/8192);
        }
    }

    if ((!avctx->rc_max_rate) != (!avctx->rc_buffer_size)) {
        av_log(avctx, AV_LOG_ERROR, "Either both buffer size and max rate or neither must be specified\n");
        return AVERROR(EINVAL);
    }

    if (avctx->rc_min_rate && avctx->rc_max_rate != avctx->rc_min_rate) {
        av_log(avctx, AV_LOG_INFO,
               "Warning min_rate > 0 but min_rate != max_rate isn't recommended!\n");
    }

    if (avctx->rc_min_rate && avctx->rc_min_rate > avctx->bit_rate) {
        av_log(avctx, AV_LOG_ERROR, "bitrate below min bitrate\n");
        return AVERROR(EINVAL);
    }

    if (avctx->rc_max_rate && avctx->rc_max_rate < avctx->bit_rate) {
        av_log(avctx, AV_LOG_ERROR, "bitrate above max bitrate\n");
        return AVERROR(EINVAL);
    }

    if (avctx->rc_max_rate &&
        avctx->rc_max_rate == avctx->bit_rate &&
        avctx->rc_max_rate != avctx->rc_min_rate) {
        av_log(avctx, AV_LOG_INFO,
               "impossible bitrate constraints, this will fail\n");
    }

    if (avctx->rc_buffer_size &&
        avctx->bit_rate * (int64_t)avctx->time_base.num >
            avctx->rc_buffer_size * (int64_t)avctx->time_base.den) {
        av_log(avctx, AV_LOG_ERROR, "VBV buffer too small for bitrate\n");
        return AVERROR(EINVAL);
    }

    if (!s->fixed_qscale &&
        avctx->bit_rate * av_q2d(avctx->time_base) >
            avctx->bit_rate_tolerance) {
        av_log(avctx, AV_LOG_WARNING,
               "bitrate tolerance %d too small for bitrate %"PRId64", overriding\n", avctx->bit_rate_tolerance, avctx->bit_rate);
        avctx->bit_rate_tolerance = 5 * avctx->bit_rate * av_q2d(avctx->time_base);
    }

    if (avctx->rc_max_rate &&
        avctx->rc_min_rate == avctx->rc_max_rate &&
        (s->codec_id == AV_CODEC_ID_MPEG1VIDEO ||
         s->codec_id == AV_CODEC_ID_MPEG2VIDEO) &&
        90000LL * (avctx->rc_buffer_size - 1) >
            avctx->rc_max_rate * 0xFFFFLL) {
        av_log(avctx, AV_LOG_INFO,
               "Warning vbv_delay will be set to 0xFFFF (=VBR) as the "
               "specified vbv buffer is too large for the given bitrate!\n");
    }

    if ((avctx->flags & AV_CODEC_FLAG_4MV) && s->codec_id != AV_CODEC_ID_MPEG4 &&
        s->codec_id != AV_CODEC_ID_H263 && s->codec_id != AV_CODEC_ID_H263P &&
        s->codec_id != AV_CODEC_ID_FLV1) {
        av_log(avctx, AV_LOG_ERROR, "4MV not supported by codec\n");
        return AVERROR(EINVAL);
    }

    if (s->obmc && avctx->mb_decision != FF_MB_DECISION_SIMPLE) {
        av_log(avctx, AV_LOG_ERROR,
               "OBMC is only supported with simple mb decision\n");
        return AVERROR(EINVAL);
    }

    if (s->quarter_sample && s->codec_id != AV_CODEC_ID_MPEG4) {
        av_log(avctx, AV_LOG_ERROR, "qpel not supported by codec\n");
        return AVERROR(EINVAL);
    }

    if (s->max_b_frames                    &&
        s->codec_id != AV_CODEC_ID_MPEG4      &&
        s->codec_id != AV_CODEC_ID_MPEG1VIDEO &&
        s->codec_id != AV_CODEC_ID_MPEG2VIDEO) {
        av_log(avctx, AV_LOG_ERROR, "B-frames not supported by codec\n");
        return AVERROR(EINVAL);
    }
    if (s->max_b_frames < 0) {
        av_log(avctx, AV_LOG_ERROR,
               "max b frames must be 0 or positive for mpegvideo based encoders\n");
        return AVERROR(EINVAL);
    }

    if ((s->codec_id == AV_CODEC_ID_MPEG4 ||
         s->codec_id == AV_CODEC_ID_H263  ||
         s->codec_id == AV_CODEC_ID_H263P) &&
        (avctx->sample_aspect_ratio.num > 255 ||
         avctx->sample_aspect_ratio.den > 255)) {
        av_log(avctx, AV_LOG_WARNING,
               "Invalid pixel aspect ratio %i/%i, limit is 255/255 reducing\n",
               avctx->sample_aspect_ratio.num, avctx->sample_aspect_ratio.den);
        av_reduce(&avctx->sample_aspect_ratio.num, &avctx->sample_aspect_ratio.den,
                   avctx->sample_aspect_ratio.num,  avctx->sample_aspect_ratio.den, 255);
    }

    if ((s->codec_id == AV_CODEC_ID_H263  ||
         s->codec_id == AV_CODEC_ID_H263P) &&
        (avctx->width  > 2048 ||
         avctx->height > 1152 )) {
        av_log(avctx, AV_LOG_ERROR, "H.263 does not support resolutions above 2048x1152\n");
        return AVERROR(EINVAL);
    }
    if ((s->codec_id == AV_CODEC_ID_H263  ||
         s->codec_id == AV_CODEC_ID_H263P) &&
        ((avctx->width &3) ||
         (avctx->height&3) )) {
        av_log(avctx, AV_LOG_ERROR, "w/h must be a multiple of 4\n");
        return AVERROR(EINVAL);
    }

    if (s->codec_id == AV_CODEC_ID_MPEG1VIDEO &&
        (avctx->width  > 4095 ||
         avctx->height > 4095 )) {
        av_log(avctx, AV_LOG_ERROR, "MPEG-1 does not support resolutions above 4095x4095\n");
        return AVERROR(EINVAL);
    }

    if (s->codec_id == AV_CODEC_ID_MPEG2VIDEO &&
        (avctx->width  > 16383 ||
         avctx->height > 16383 )) {
        av_log(avctx, AV_LOG_ERROR, "MPEG-2 does not support resolutions above 16383x16383\n");
        return AVERROR(EINVAL);
    }

    if (s->codec_id == AV_CODEC_ID_RV10 &&
        (avctx->width &15 ||
         avctx->height&15 )) {
        av_log(avctx, AV_LOG_ERROR, "width and height must be a multiple of 16\n");
        return AVERROR(EINVAL);
    }

    if (s->codec_id == AV_CODEC_ID_RV20 &&
        (avctx->width &3 ||
         avctx->height&3 )) {
        av_log(avctx, AV_LOG_ERROR, "width and height must be a multiple of 4\n");
        return AVERROR(EINVAL);
    }

    if ((s->codec_id == AV_CODEC_ID_WMV1 ||
         s->codec_id == AV_CODEC_ID_WMV2) &&
         avctx->width & 1) {
        av_log(avctx, AV_LOG_ERROR, "width must be multiple of 2\n");
        return AVERROR(EINVAL);
    }

    if ((avctx->flags & (AV_CODEC_FLAG_INTERLACED_DCT | AV_CODEC_FLAG_INTERLACED_ME)) &&
        s->codec_id != AV_CODEC_ID_MPEG4 && s->codec_id != AV_CODEC_ID_MPEG2VIDEO) {
        av_log(avctx, AV_LOG_ERROR, "interlacing not supported by codec\n");
        return AVERROR(EINVAL);
    }

#if FF_API_PRIVATE_OPT
    FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->mpeg_quant)
        s->mpeg_quant = avctx->mpeg_quant;
    FF_ENABLE_DEPRECATION_WARNINGS
#endif

    // FIXME mpeg2 uses that too
    if (s->mpeg_quant && (   s->codec_id != AV_CODEC_ID_MPEG4
                          && s->codec_id != AV_CODEC_ID_MPEG2VIDEO)) {
        av_log(avctx, AV_LOG_ERROR,
               "mpeg2 style quantization not supported by codec\n");
        return AVERROR(EINVAL);
    }

    if ((s->mpv_flags & FF_MPV_FLAG_CBP_RD) && !avctx->trellis) {
        av_log(avctx, AV_LOG_ERROR, "CBP RD needs trellis quant\n");
        return AVERROR(EINVAL);
    }

    if ((s->mpv_flags & FF_MPV_FLAG_QP_RD) &&
        avctx->mb_decision != FF_MB_DECISION_RD) {
        av_log(avctx, AV_LOG_ERROR, "QP RD needs mbd=2\n");
        return AVERROR(EINVAL);
    }

    if ((s->mpv_flags & FF_MPV_FLAG_QP_RD) &&
            (s->codec_id == AV_CODEC_ID_AMV ||
             s->codec_id == AV_CODEC_ID_MJPEG)) {
        // Used to produce garbage with MJPEG.
        av_log(avctx, AV_LOG_ERROR,
               "QP RD is no longer compatible with MJPEG or AMV\n");
        return AVERROR(EINVAL);
    }

#if FF_API_PRIVATE_OPT
FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->scenechange_threshold)
        s->scenechange_threshold = avctx->scenechange_threshold;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

    if (s->scenechange_threshold < 1000000000 &&
        (avctx->flags & AV_CODEC_FLAG_CLOSED_GOP)) {
        av_log(avctx, AV_LOG_ERROR,
               "closed gop with scene change detection are not supported yet, "
               "set threshold to 1000000000\n");
        return AVERROR_PATCHWELCOME;
    }

    if (avctx->flags & AV_CODEC_FLAG_LOW_DELAY) {
        if (s->codec_id != AV_CODEC_ID_MPEG2VIDEO &&
            s->strict_std_compliance >= FF_COMPLIANCE_NORMAL) {
            av_log(avctx, AV_LOG_ERROR,
                   "low delay forcing is only available for mpeg2, "
                   "set strict_std_compliance to 'unofficial' or lower in order to allow it\n");
            return AVERROR(EINVAL);
        }
        if (s->max_b_frames != 0) {
            av_log(avctx, AV_LOG_ERROR,
                   "B-frames cannot be used with low delay\n");
            return AVERROR(EINVAL);
        }
    }

    if (s->q_scale_type == 1) {
        if (avctx->qmax > 28) {
            av_log(avctx, AV_LOG_ERROR,
                   "non linear quant only supports qmax <= 28 currently\n");
            return AVERROR_PATCHWELCOME;
        }
    }

    if (avctx->slices > 1 &&
        (avctx->codec_id == AV_CODEC_ID_FLV1 || avctx->codec_id == AV_CODEC_ID_H261)) {
        av_log(avctx, AV_LOG_ERROR, "Multiple slices are not supported by this codec\n");
        return AVERROR(EINVAL);
    }

    if (avctx->thread_count > 1         &&
        s->codec_id != AV_CODEC_ID_MPEG4      &&
        s->codec_id != AV_CODEC_ID_MPEG1VIDEO &&
        s->codec_id != AV_CODEC_ID_MPEG2VIDEO &&
        s->codec_id != AV_CODEC_ID_MJPEG      &&
        (s->codec_id != AV_CODEC_ID_H263P)) {
        av_log(avctx, AV_LOG_ERROR,
               "multi threaded encoding not supported by codec\n");
        return AVERROR_PATCHWELCOME;
    }

    if (avctx->thread_count < 1) {
        av_log(avctx, AV_LOG_ERROR,
               "automatic thread number detection not supported by codec, "
               "patch welcome\n");
        return AVERROR_PATCHWELCOME;
    }

    if (!avctx->time_base.den || !avctx->time_base.num) {
        av_log(avctx, AV_LOG_ERROR, "framerate not set\n");
        return AVERROR(EINVAL);
    }

#if FF_API_PRIVATE_OPT
FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->b_frame_strategy)
        s->b_frame_strategy = avctx->b_frame_strategy;
    if (avctx->b_sensitivity != 40)
        s->b_sensitivity = avctx->b_sensitivity;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

    if (s->b_frame_strategy && (avctx->flags & AV_CODEC_FLAG_PASS2)) {
        av_log(avctx, AV_LOG_INFO,
               "notice: b_frame_strategy only affects the first pass\n");
        s->b_frame_strategy = 0;
    }

    i = av_gcd(avctx->time_base.den, avctx->time_base.num);
    if (i > 1) {
        av_log(avctx, AV_LOG_INFO, "removing common factors from framerate\n");
        avctx->time_base.den /= i;
        avctx->time_base.num /= i;
        //return -1;
    }

    if (s->mpeg_quant || s->codec_id == AV_CODEC_ID_MPEG1VIDEO || s->codec_id == AV_CODEC_ID_MPEG2VIDEO || s->codec_id == AV_CODEC_ID_MJPEG || s->codec_id==AV_CODEC_ID_AMV) {
        // (a + x * 3 / 8) / x
        s->intra_quant_bias = 3 << (QUANT_BIAS_SHIFT - 3);
        s->inter_quant_bias = 0;
    } else {
        s->intra_quant_bias = 0;
        // (a - x / 4) / x
        s->inter_quant_bias = -(1 << (QUANT_BIAS_SHIFT - 2));
    }

    if (avctx->qmin > avctx->qmax || avctx->qmin <= 0) {
        av_log(avctx, AV_LOG_ERROR, "qmin and or qmax are invalid, they must be 0 < min <= max\n");
        return AVERROR(EINVAL);
    }

    av_log(avctx, AV_LOG_DEBUG, "intra_quant_bias = %d inter_quant_bias = %d\n",s->intra_quant_bias,s->inter_quant_bias);

    if (avctx->codec_id == AV_CODEC_ID_MPEG4 &&
        avctx->time_base.den > (1 << 16) - 1) {
        av_log(avctx, AV_LOG_ERROR,
               "timebase %d/%d not supported by MPEG 4 standard, "
               "the maximum admitted value for the timebase denominator "
               "is %d\n", avctx->time_base.num, avctx->time_base.den,
               (1 << 16) - 1);
        return AVERROR(EINVAL);
    }
    s->time_increment_bits = av_log2(avctx->time_base.den - 1) + 1;

    switch (avctx->codec->id) {
    case AV_CODEC_ID_MPEG1VIDEO:
        s->out_format = FMT_MPEG1;
        s->low_delay  = !!(avctx->flags & AV_CODEC_FLAG_LOW_DELAY);
        avctx->delay  = s->low_delay ? 0 : (s->max_b_frames + 1);
        break;
    case AV_CODEC_ID_MPEG2VIDEO:
        s->out_format = FMT_MPEG1;
        s->low_delay  = !!(avctx->flags & AV_CODEC_FLAG_LOW_DELAY);
        avctx->delay  = s->low_delay ? 0 : (s->max_b_frames + 1);
        s->rtp_mode   = 1;
        break;
    case AV_CODEC_ID_MJPEG:
    case AV_CODEC_ID_AMV:
        s->out_format = FMT_MJPEG;
        s->intra_only = 1; /* force intra only for jpeg */
        if (!CONFIG_MJPEG_ENCODER)
            return AVERROR_ENCODER_NOT_FOUND;
        if ((ret = ff_mjpeg_encode_init(s)) < 0)
            return ret;
        avctx->delay = 0;
        s->low_delay = 1;
        break;
    case AV_CODEC_ID_H261:
        if (!CONFIG_H261_ENCODER)
            return AVERROR_ENCODER_NOT_FOUND;
        if (ff_h261_get_picture_format(s->width, s->height) < 0) {
            av_log(avctx, AV_LOG_ERROR,
                   "The specified picture size of %dx%d is not valid for the "
                   "H.261 codec.\nValid sizes are 176x144, 352x288\n",
                    s->width, s->height);
            return AVERROR(EINVAL);
        }
        s->out_format = FMT_H261;
        avctx->delay  = 0;
        s->low_delay  = 1;
        s->rtp_mode   = 0; /* Sliced encoding not supported */
        break;
    case AV_CODEC_ID_H263:
        if (!CONFIG_H263_ENCODER)
            return AVERROR_ENCODER_NOT_FOUND;
        if (ff_match_2uint16(ff_h263_format, FF_ARRAY_ELEMS(ff_h263_format),
                             s->width, s->height) == 8) {
            av_log(avctx, AV_LOG_ERROR,
                   "The specified picture size of %dx%d is not valid for "
                   "the H.263 codec.\nValid sizes are 128x96, 176x144, "
                   "352x288, 704x576, and 1408x1152. "
                   "Try H.263+.\n", s->width, s->height);
            return AVERROR(EINVAL);
        }
        s->out_format = FMT_H263;
        avctx->delay  = 0;
        s->low_delay  = 1;
        break;
    case AV_CODEC_ID_H263P:
        s->out_format = FMT_H263;
        s->h263_plus  = 1;
        /* Fx */
        s->h263_aic        = (avctx->flags & AV_CODEC_FLAG_AC_PRED) ? 1 : 0;
        s->modified_quant  = s->h263_aic;
        s->loop_filter     = (avctx->flags & AV_CODEC_FLAG_LOOP_FILTER) ? 1 : 0;
        s->unrestricted_mv = s->obmc || s->loop_filter || s->umvplus;

        /* /Fx */
        /* These are just to be sure */
        avctx->delay = 0;
        s->low_delay = 1;
        break;
    case AV_CODEC_ID_FLV1:
        s->out_format      = FMT_H263;
        s->h263_flv        = 2; /* format = 1; 11-bit codes */
        s->unrestricted_mv = 1;
        s->rtp_mode  = 0; /* don't allow GOB */
        avctx->delay = 0;
        s->low_delay = 1;
        break;
    case AV_CODEC_ID_RV10:
        s->out_format = FMT_H263;
        avctx->delay  = 0;
        s->low_delay  = 1;
        break;
    case AV_CODEC_ID_RV20:
        s->out_format      = FMT_H263;
        avctx->delay       = 0;
        s->low_delay       = 1;
        s->modified_quant  = 1;
        s->h263_aic        = 1;
        s->h263_plus       = 1;
        s->loop_filter     = 1;
        s->unrestricted_mv = 0;
        break;
    case AV_CODEC_ID_MPEG4:
        s->out_format      = FMT_H263;
        s->h263_pred       = 1;
        s->unrestricted_mv = 1;
        s->low_delay       = s->max_b_frames ? 0 : 1;
        avctx->delay       = s->low_delay ? 0 : (s->max_b_frames + 1);
        break;
    case AV_CODEC_ID_MSMPEG4V2:
        s->out_format      = FMT_H263;
        s->h263_pred       = 1;
        s->unrestricted_mv = 1;
        s->msmpeg4_version = 2;
        avctx->delay       = 0;
        s->low_delay       = 1;
        break;
    case AV_CODEC_ID_MSMPEG4V3:
        s->out_format        = FMT_H263;
        s->h263_pred         = 1;
        s->unrestricted_mv   = 1;
        s->msmpeg4_version   = 3;
        s->flipflop_rounding = 1;
        avctx->delay         = 0;
        s->low_delay         = 1;
        break;
    case AV_CODEC_ID_WMV1:
        s->out_format        = FMT_H263;
        s->h263_pred         = 1;
        s->unrestricted_mv   = 1;
        s->msmpeg4_version   = 4;
        s->flipflop_rounding = 1;
        avctx->delay         = 0;
        s->low_delay         = 1;
        break;
    case AV_CODEC_ID_WMV2:
        s->out_format        = FMT_H263;
        s->h263_pred         = 1;
        s->unrestricted_mv   = 1;
        s->msmpeg4_version   = 5;
        s->flipflop_rounding = 1;
        avctx->delay         = 0;
        s->low_delay         = 1;
        break;
    default:
        return AVERROR(EINVAL);
    }

#if FF_API_PRIVATE_OPT
    FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->noise_reduction)
        s->noise_reduction = avctx->noise_reduction;
    FF_ENABLE_DEPRECATION_WARNINGS
#endif

    avctx->has_b_frames = !s->low_delay;

    s->encoding = 1;

    s->progressive_frame    =
    s->progressive_sequence = !(avctx->flags & (AV_CODEC_FLAG_INTERLACED_DCT |
                                                AV_CODEC_FLAG_INTERLACED_ME) ||
                                s->alternate_scan);

    /* init */
    ff_mpv_idct_init(s);
    if ((ret = ff_mpv_common_init(s)) < 0)
        return ret;

    ff_fdctdsp_init(&s->fdsp, avctx);
    ff_me_cmp_init(&s->mecc, avctx);
    ff_mpegvideoencdsp_init(&s->mpvencdsp, avctx);
    ff_pixblockdsp_init(&s->pdsp, avctx);
    ff_qpeldsp_init(&s->qdsp);

    if (s->msmpeg4_version) {
        int ac_stats_size = 2 * 2 * (MAX_LEVEL + 1) *  (MAX_RUN + 1) * 2 * sizeof(int);
        if (!(s->ac_stats = av_mallocz(ac_stats_size)))
            return AVERROR(ENOMEM);
    }

    if (!(avctx->stats_out = av_mallocz(256))               ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_intra_matrix,          32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_chroma_intra_matrix,   32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_inter_matrix,          32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_intra_matrix16,        32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_chroma_intra_matrix16, 32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->q_inter_matrix16,        32) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->input_picture,           MAX_PICTURE_COUNT) ||
        !FF_ALLOCZ_TYPED_ARRAY(s->reordered_input_picture, MAX_PICTURE_COUNT))
        return AVERROR(ENOMEM);

    if (s->noise_reduction) {
        if (!FF_ALLOCZ_TYPED_ARRAY(s->dct_offset, 2))
            return AVERROR(ENOMEM);
    }

    ff_dct_encode_init(s);

    if ((CONFIG_H263P_ENCODER || CONFIG_RV20_ENCODER) && s->modified_quant)
        s->chroma_qscale_table = ff_h263_chroma_qscale_table;

    if (s->slice_context_count > 1) {
        s->rtp_mode = 1;

        if (avctx->codec_id == AV_CODEC_ID_H263P)
            s->h263_slice_structured = 1;
    }

    s->quant_precision = 5;

#if FF_API_PRIVATE_OPT
FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->frame_skip_threshold)
        s->frame_skip_threshold = avctx->frame_skip_threshold;
    if (avctx->frame_skip_factor)
        s->frame_skip_factor = avctx->frame_skip_factor;
    if (avctx->frame_skip_exp)
        s->frame_skip_exp = avctx->frame_skip_exp;
    if (avctx->frame_skip_cmp != FF_CMP_DCTMAX)
        s->frame_skip_cmp = avctx->frame_skip_cmp;
FF_ENABLE_DEPRECATION_WARNINGS
#endif

    ff_set_cmp(&s->mecc, s->mecc.ildct_cmp,      avctx->ildct_cmp);
    ff_set_cmp(&s->mecc, s->mecc.frame_skip_cmp, s->frame_skip_cmp);

    if (CONFIG_H261_ENCODER && s->out_format == FMT_H261)
        ff_h261_encode_init(s);
    if (CONFIG_H263_ENCODER && s->out_format == FMT_H263)
        ff_h263_encode_init(s);
    if (CONFIG_MSMPEG4_ENCODER && s->msmpeg4_version)
        if ((ret = ff_msmpeg4_encode_init(s)) < 0)
            return ret;
    if ((CONFIG_MPEG1VIDEO_ENCODER || CONFIG_MPEG2VIDEO_ENCODER)
        && s->out_format == FMT_MPEG1)
        ff_mpeg1_encode_init(s);

    /* init q matrix */
    for (i = 0; i < 64; i++) {
        int j = s->idsp.idct_permutation[i];
        if (CONFIG_MPEG4_ENCODER && s->codec_id == AV_CODEC_ID_MPEG4 &&
            s->mpeg_quant) {
            s->intra_matrix[j] = ff_mpeg4_default_intra_matrix[i];
            s->inter_matrix[j] = ff_mpeg4_default_non_intra_matrix[i];
        } else if (s->out_format == FMT_H263 || s->out_format == FMT_H261) {
            s->intra_matrix[j] =
            s->inter_matrix[j] = ff_mpeg1_default_non_intra_matrix[i];
        } else {
            /* MPEG-1/2 */
            s->chroma_intra_matrix[j] =
            s->intra_matrix[j] = ff_mpeg1_default_intra_matrix[i];
            s->inter_matrix[j] = ff_mpeg1_default_non_intra_matrix[i];
        }
        if (avctx->intra_matrix)
            s->intra_matrix[j] = avctx->intra_matrix[i];
        if (avctx->inter_matrix)
            s->inter_matrix[j] = avctx->inter_matrix[i];
    }

    /* precompute matrix */
    /* for mjpeg, we do include qscale in the matrix */
    if (s->out_format != FMT_MJPEG) {
        ff_convert_matrix(s, s->q_intra_matrix, s->q_intra_matrix16,
                          s->intra_matrix, s->intra_quant_bias, avctx->qmin,
                          31, 1);
        ff_convert_matrix(s, s->q_inter_matrix, s->q_inter_matrix16,
                          s->inter_matrix, s->inter_quant_bias, avctx->qmin,
                          31, 0);
    }

    if ((ret = ff_rate_control_init(s)) < 0)
        return ret;

#if FF_API_PRIVATE_OPT
    FF_DISABLE_DEPRECATION_WARNINGS
    if (avctx->brd_scale)
        s->brd_scale = avctx->brd_scale;

    if (avctx->prediction_method)
        s->pred = avctx->prediction_method + 1;
    FF_ENABLE_DEPRECATION_WARNINGS
#endif

    if (s->b_frame_strategy == 2) {
        for (i = 0; i < s->max_b_frames + 2; i++) {
            s->tmp_frames[i] = av_frame_alloc();
            if (!s->tmp_frames[i])
                return AVERROR(ENOMEM);

            s->tmp_frames[i]->format = AV_PIX_FMT_YUV420P;
            s->tmp_frames[i]->width  = s->width  >> s->brd_scale;
            s->tmp_frames[i]->height = s->height >> s->brd_scale;

            ret = av_frame_get_buffer(s->tmp_frames[i], 0);
            if (ret < 0)
                return ret;
        }
    }

    cpb_props = ff_add_cpb_side_data(avctx);
    if (!cpb_props)
        return AVERROR(ENOMEM);
    cpb_props->max_bitrate = avctx->rc_max_rate;
    cpb_props->min_bitrate = avctx->rc_min_rate;
    cpb_props->avg_bitrate = avctx->bit_rate;
    cpb_props->buffer_size = avctx->rc_buffer_size;

    return 0;
}