[FFmpeg-devel] [PATCH] avcodec: Add MediaFoundation encoder wrapper

[James Almer]

On 5/9/2020 6:41 PM, Martin Storsjö wrote:
> +#define MF_ENCODER(MEDIATYPE, NAME, ID, OPTS, EXTRA) \
> +    static const AVClass ff_ ## NAME ## _mf_encoder_class = {                  \
> +        .class_name = #NAME "_mf",                                             \
> +        .item_name  = av_default_item_name,                                    \
> +        .option     = OPTS,                                                    \
> +        .version    = LIBAVUTIL_VERSION_INT,                                   \
> +    };                                                                         \
> +    AVCodec ff_ ## NAME ## _mf_encoder = {                                     \
> +        .priv_class     = &ff_ ## NAME ## _mf_encoder_class,                   \
> +        .name           = #NAME "_mf",                                         \
> +        .long_name      = NULL_IF_CONFIG_SMALL(#ID " via MediaFoundation"),    \
> +        .type           = AVMEDIA_TYPE_ ## MEDIATYPE,                          \
> +        .id             = AV_CODEC_ID_ ## ID,                                  \
> +        .priv_data_size = sizeof(MFContext),                                   \
> +        .init           = mf_init,                                             \
> +        .close          = mf_close,                                            \
> +        .send_frame     = mf_send_frame,                                       \
> +        .receive_packet = mf_receive_packet,                                   \
> +        EXTRA                                                                  \
> +        .capabilities   = AV_CODEC_CAP_DELAY,                                  \

Should probably also be AV_CODEC_CAP_HYBRID.

> +        .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |                       \
> +                          FF_CODEC_CAP_INIT_CLEANUP,                           \
> +    };
> +
> +#define AFMTS \
> +        .sample_fmts    = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,    \
> +                                                         AV_SAMPLE_FMT_NONE },
> +
> +MF_ENCODER(AUDIO, aac,         AAC, NULL, AFMTS);
> +MF_ENCODER(AUDIO, ac3,         AC3, NULL, AFMTS);
> +MF_ENCODER(AUDIO, mp3,         MP3, NULL, AFMTS);
> +
> +#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
> +static const AVOption venc_opts[] = {
> +    {"rate_control",  "Select rate control mode", OFFSET(opt_enc_rc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, INT_MAX, VE, "rate_control"},
> +    { "default",      "Default mode", 0, AV_OPT_TYPE_CONST, {.i64 = -1}, 0, 0, VE, "rate_control"},
> +    { "cbr",          "CBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_CBR}, 0, 0, VE, "rate_control"},
> +    { "pc_vbr",       "Peak constrained VBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_PeakConstrainedVBR}, 0, 0, VE, "rate_control"},
> +    { "u_vbr",        "Unconstrained VBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_UnconstrainedVBR}, 0, 0, VE, "rate_control"},
> +    { "quality",      "Quality mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_Quality}, 0, 0, VE, "rate_control" },
> +    // The following rate_control modes require Windows 8.
> +    { "ld_vbr",       "Low delay VBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_LowDelayVBR}, 0, 0, VE, "rate_control"},
> +    { "g_vbr",        "Global VBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_GlobalVBR}, 0, 0, VE, "rate_control" },
> +    { "gld_vbr",      "Global low delay VBR mode", 0, AV_OPT_TYPE_CONST, {.i64 = ff_eAVEncCommonRateControlMode_GlobalLowDelayVBR}, 0, 0, VE, "rate_control"},
> +    {"quality",       "Quality", OFFSET(opt_enc_quality), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 100, VE},
> +    {"hw_encoding",   "Force hardware encoding", OFFSET(opt_enc_hw), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, VE, "hw_encoding"},

Can't you attempt to init using hw by default and if that fails
gracefully fallback to the sw implementation?
This option could instead just attempt to force disable or enable hw
(deafault -1/auto), and if hw can't be used when forced it would just
abort instead of falling back to sw.

> +    {NULL}
> +};