[FFmpeg-devel] [PATCH] avcodec/mediacodecdec: add low latency decoding

["zhilizhao(赵志立)"]

> On May 22, 2023, at 14:52, xufuji456 <839789740 at qq.com> wrote:
> 
> The low-latency decoding mode has available in Android api 30.
> See https://developer.android.google.cn/reference/android/media/MediaCodec?hl=en#PARAMETER_KEY_LOW_LATENCY
> 
> Signed-off-by: xufuji456 <839789740 at qq.com>
> ---
> libavcodec/mediacodecdec.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/libavcodec/mediacodecdec.c b/libavcodec/mediacodecdec.c
> index 21464900d1..52c30e1173 100644
> --- a/libavcodec/mediacodecdec.c
> +++ b/libavcodec/mediacodecdec.c
> @@ -395,6 +395,12 @@ static av_cold int mediacodec_decode_init(AVCodecContext *avctx)
>     ff_AMediaFormat_setInt32(format, "width", avctx->width);
>     ff_AMediaFormat_setInt32(format, "height", avctx->height);
> 
> +    sdk_int = ff_Build_SDK_INT(avctx);
> +    // low-latency mode: available in Android api 30
> +    if (sdk_int >= 30 && (avctx->flags & AV_CODEC_FLAG_LOW_DELAY)) {
> +        ff_AMediaFormat_setInt32(format, "low-latency", 1);
> +    }
> +

Please remove the check on api level. ff_Build_SDK_INT() can fail,
and set an unknown option for api level < 30 should be fine.

>     s->ctx = av_mallocz(sizeof(*s->ctx));
>     if (!s->ctx) {
>         av_log(avctx, AV_LOG_ERROR, "Failed to allocate MediaCodecDecContext\n");
> @@ -414,7 +420,6 @@ static av_cold int mediacodec_decode_init(AVCodecContext *avctx)
>            "MediaCodec started successfully: codec = %s, ret = %d\n",
>            s->ctx->codec_name, ret);
> 
> -    sdk_int = ff_Build_SDK_INT(avctx);
>     /* ff_Build_SDK_INT can fail when target API < 24 and JVM isn't available.
>      * If we don't check sdk_int > 0, the workaround might be enabled by
>      * mistake.
> -- 
> 2.32.0 (Apple Git-132)
> 
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