Hi,
the concept is generally ok, but I have a few comments on the
implementation.
Quoting Xiang, Haihao (2022-07-25 06:30:51)
> +static const AVCodec *choose_decoder2(InputStream *ist, OptionsContext *o,
> AVFormatContext *s, AVStream *st)
> +{
> + char *codec_name = NULL;
> +
> + MATCH_PER_STREAM_OPT(codec_names, str, codec_name, s, st);
> + if (codec_name) {
> + const AVCodec *codec = find_codec_or_die(codec_name,
> st->codecpar->codec_type, 0);
> + st->codecpar->codec_id = codec->id;
> + if (recast_media && st->codecpar->codec_type != codec->type)
> + st->codecpar->codec_type = codec->type;
> + return codec;
> + } else {
> + if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
> + ist->hwaccel_id == HWACCEL_GENERIC &&
> + ist->hwaccel_device_type != AV_HWDEVICE_TYPE_NONE) {
> + const AVCodec *p;
'p' is a rather weird name for an AVCodec instance, I'd expect 'c' or
'codec' or something like that
> + void *i = 0;
NULL, it's a pointer
> +
> + while ((p = av_codec_iterate(&i))) {
> + int j;
> +
> + if (p->id != st->codecpar->codec_id ||
> + !av_codec_is_decoder(p) ||
> + !avcodec_get_hw_config(p, 0))
> + continue;
> +
> + for (j = 0; ;j++) {
for (int j = 0; config = avcodec_get_hw_config(p, j); j++)
gets rid of the explicit check in the loop and also
avcodec_get_hw_config() in the condition above
> + const AVCodecHWConfig *config = avcodec_get_hw_config(p,
> j);
> +
> + if (!config)
> + break;
> +
> + if (config->device_type == ist->hwaccel_device_type)
> + return p;
> + }
> + }
> + }
> +
> + return avcodec_find_decoder(st->codecpar->codec_id);
> + }
> +}
> +
> /* Add all the streams from the given input file to the global
> * list of input streams. */
> static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
> @@ -973,7 +1015,7 @@ static void add_input_streams(OptionsContext *o,
> AVFormatContext *ic)
> ist->hwaccel_pix_fmt = AV_PIX_FMT_NONE;
> }
>
> - ist->dec = choose_decoder(o, ic, st);
> + ist->dec = choose_decoder2(ist, o, ic, st);
I don't like adding a new function that partially duplicates
choose_decoder() and has a non-descriptive name. Just extend
choose_decoder() by passing hwaccel_id and hwaccel_device_type to it.
--
Anton Khirnov
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