On 03/05/2022 01:14, Soft Works wrote:
-----Original Message----- From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of Mark Thompson Sent: Tuesday, May 3, 2022 2:09 AM To: FFmpeg development discussions and patches <ffmpeg- de...@ffmpeg.org> Subject: [FFmpeg-devel] [PATCH] hwcontext: Skip derivation checking for an existing device if options are setIf options are set then the user definitely intends to create a new device, so we shouldn't attempt to return an existing one. --- libavutil/hwcontext.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/libavutil/hwcontext.c b/libavutil/hwcontext.c index ab9ad3703e..c4e01e0e78 100644 --- a/libavutil/hwcontext.c +++ b/libavutil/hwcontext.c @@ -653,18 +653,24 @@ int av_hwdevice_ctx_create_derived_opts(AVBufferRef **dst_ref_ptr, AVHWDeviceContext *dst_ctx, *tmp_ctx; int ret = 0; - tmp_ref = src_ref; - while (tmp_ref) { - tmp_ctx = (AVHWDeviceContext*)tmp_ref->data; - if (tmp_ctx->type == type) { - dst_ref = av_buffer_ref(tmp_ref); - if (!dst_ref) { - ret = AVERROR(ENOMEM); - goto fail; + // If we were derived (possibly transitively) from a device of the + // target type then we want to return that original device, unless + // options are set in which case we can skip this check because it + // is definitely intended to create a new device. + if (!options) { + tmp_ref = src_ref; + while (tmp_ref) { + tmp_ctx = (AVHWDeviceContext*)tmp_ref->data; + if (tmp_ctx->type == type) { + dst_ref = av_buffer_ref(tmp_ref); + if (!dst_ref) { + ret = AVERROR(ENOMEM); + goto fail; + } + goto done; } - goto done; + tmp_ref = tmp_ctx->internal->source_device; } - tmp_ref = tmp_ctx->internal->source_device; } dst_ref = av_hwdevice_ctx_alloc(type); --This doesn't implement the matching of device parameters, which you were talking about: You said that when deriving a device, an existing device should only be returned when the parameters are the same. This patch is doing something quite different.
Why would that be useful in the current design? As the documentation on create_derived states, it has two independent uses - this is the "retrieve source device" case, and for that it does not make sense to set the options argument because no new device is being created. I will clarify the doxy on _opts. - Mark _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
