mpv/video/hwdec.c

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3.8 KiB
C
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#include <pthread.h>
#include <assert.h>
#include <libavutil/hwcontext.h>
#include "config.h"
#include "hwdec.h"
struct mp_hwdec_devices {
pthread_mutex_t lock;
vo_gpu: make it possible to load multiple hwdec interop drivers Make the VO<->decoder interface capable of supporting multiple hwdec APIs at once. The main gain is that this simplifies autoprobing a lot. Before this change, it could happen that the VO loaded the "wrong" hwdec API, and the decoder was stuck with the choice (breaking hw decoding). With the change applied, the VO simply loads all available APIs, so autoprobing trickery is left entirely to the decoder. In the past, we were quite careful about not accidentally loading the wrong interop drivers. This was in part to make sure autoprobing works, but also because libva had this obnoxious bug of dumping garbage to stderr when using the API. libva was fixed, so this is not a problem anymore. The --opengl-hwdec-interop option is changed in various ways (again...), and renamed to --gpu-hwdec-interop. It does not have much use anymore, other than debugging. It's notable that the order in the hwdec interop array ra_hwdec_drivers[] still matters if multiple drivers support the same image formats, so the option can explicitly force one, if that should ever be necessary, or more likely, for debugging. One example are the ra_hwdec_d3d11egl and ra_hwdec_d3d11eglrgb drivers, which both support d3d11 input. vo_gpu now always loads the interop lazily by default, but when it does, it loads them all. vo_opengl_cb now always loads them when the GL context handle is initialized. I don't expect that this causes any problems. It's now possible to do things like changing between vdpau and nvdec decoding at runtime. This is also preparation for cleaning up vd_lavc.c hwdec autoprobing. It's another reason why hwdec_devices_request_all() does not take a hwdec type anymore.
2017-12-01 04:05:00 +00:00
struct mp_hwdec_ctx **hwctxs;
int num_hwctxs;
void (*load_api)(void *ctx, int imgfmt);
void *load_api_ctx;
};
struct mp_hwdec_devices *hwdec_devices_create(void)
{
struct mp_hwdec_devices *devs = talloc_zero(NULL, struct mp_hwdec_devices);
pthread_mutex_init(&devs->lock, NULL);
return devs;
}
void hwdec_devices_destroy(struct mp_hwdec_devices *devs)
{
if (!devs)
return;
vo_gpu: make it possible to load multiple hwdec interop drivers Make the VO<->decoder interface capable of supporting multiple hwdec APIs at once. The main gain is that this simplifies autoprobing a lot. Before this change, it could happen that the VO loaded the "wrong" hwdec API, and the decoder was stuck with the choice (breaking hw decoding). With the change applied, the VO simply loads all available APIs, so autoprobing trickery is left entirely to the decoder. In the past, we were quite careful about not accidentally loading the wrong interop drivers. This was in part to make sure autoprobing works, but also because libva had this obnoxious bug of dumping garbage to stderr when using the API. libva was fixed, so this is not a problem anymore. The --opengl-hwdec-interop option is changed in various ways (again...), and renamed to --gpu-hwdec-interop. It does not have much use anymore, other than debugging. It's notable that the order in the hwdec interop array ra_hwdec_drivers[] still matters if multiple drivers support the same image formats, so the option can explicitly force one, if that should ever be necessary, or more likely, for debugging. One example are the ra_hwdec_d3d11egl and ra_hwdec_d3d11eglrgb drivers, which both support d3d11 input. vo_gpu now always loads the interop lazily by default, but when it does, it loads them all. vo_opengl_cb now always loads them when the GL context handle is initialized. I don't expect that this causes any problems. It's now possible to do things like changing between vdpau and nvdec decoding at runtime. This is also preparation for cleaning up vd_lavc.c hwdec autoprobing. It's another reason why hwdec_devices_request_all() does not take a hwdec type anymore.
2017-12-01 04:05:00 +00:00
assert(!devs->num_hwctxs); // must have been hwdec_devices_remove()ed
assert(!devs->load_api); // must have been unset
pthread_mutex_destroy(&devs->lock);
talloc_free(devs);
}
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
struct mp_hwdec_ctx *hwdec_devices_get_by_lavc(struct mp_hwdec_devices *devs,
int av_hwdevice_type)
{
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
struct mp_hwdec_ctx *res = NULL;
pthread_mutex_lock(&devs->lock);
for (int n = 0; n < devs->num_hwctxs; n++) {
struct mp_hwdec_ctx *dev = devs->hwctxs[n];
if (dev->av_device_ref) {
AVHWDeviceContext *hwctx = (void *)dev->av_device_ref->data;
if (hwctx->type == av_hwdevice_type) {
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
res = dev;
break;
}
}
}
pthread_mutex_unlock(&devs->lock);
return res;
}
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
struct AVBufferRef *hwdec_devices_get_lavc(struct mp_hwdec_devices *devs,
int av_hwdevice_type)
{
struct mp_hwdec_ctx *ctx = hwdec_devices_get_by_lavc(devs, av_hwdevice_type);
if (!ctx)
return NULL;
return av_buffer_ref(ctx->av_device_ref);
}
struct mp_hwdec_ctx *hwdec_devices_get_first(struct mp_hwdec_devices *devs)
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
{
return hwdec_devices_get_n(devs, 0);
}
struct mp_hwdec_ctx *hwdec_devices_get_n(struct mp_hwdec_devices *devs, int n)
{
pthread_mutex_lock(&devs->lock);
video: rewrite filtering glue code Get rid of the old vf.c code. Replace it with a generic filtering framework, which can potentially handle more than just --vf. At least reimplementing --af with this code is planned. This changes some --vf semantics (including runtime behavior and the "vf" command). The most important ones are listed in interface-changes. vf_convert.c is renamed to f_swscale.c. It is now an internal filter that can not be inserted by the user manually. f_lavfi.c is a refactor of player/lavfi.c. The latter will be removed once --lavfi-complex is reimplemented on top of f_lavfi.c. (which is conceptually easy, but a big mess due to the data flow changes). The existing filters are all changed heavily. The data flow of the new filter framework is different. Especially EOF handling changes - EOF is now a "frame" rather than a state, and must be passed through exactly once. Another major thing is that all filters must support dynamic format changes. The filter reconfig() function goes away. (This sounds complex, but since all filters need to handle EOF draining anyway, they can use the same code, and it removes the mess with reconfig() having to predict the output format, which completely breaks with libavfilter anyway.) In addition, there is no automatic format negotiation or conversion. libavfilter's primitive and insufficient API simply doesn't allow us to do this in a reasonable way. Instead, filters can use f_autoconvert as sub-filter, and tell it which formats they support. This filter will in turn add actual conversion filters, such as f_swscale, to perform necessary format changes. vf_vapoursynth.c uses the same basic principle of operation as before, but with worryingly different details in data flow. Still appears to work. The hardware deint filters (vf_vavpp.c, vf_d3d11vpp.c, vf_vdpaupp.c) are heavily changed. Fortunately, they all used refqueue.c, which is for sharing the data flow logic (especially for managing future/past surfaces and such). It turns out it can be used to factor out most of the data flow. Some of these filters accepted software input. Instead of having ad-hoc upload code in each filter, surface upload is now delegated to f_autoconvert, which can use f_hwupload to perform this. Exporting VO capabilities is still a big mess (mp_stream_info stuff). The D3D11 code drops the redundant image formats, and all code uses the hw_subfmt (sw_format in FFmpeg) instead. Although that too seems to be a big mess for now. f_async_queue is unused.
2018-01-16 10:53:44 +00:00
struct mp_hwdec_ctx *res = n < devs->num_hwctxs ? devs->hwctxs[n] : NULL;
pthread_mutex_unlock(&devs->lock);
return res;
}
void hwdec_devices_add(struct mp_hwdec_devices *devs, struct mp_hwdec_ctx *ctx)
{
pthread_mutex_lock(&devs->lock);
vo_gpu: make it possible to load multiple hwdec interop drivers Make the VO<->decoder interface capable of supporting multiple hwdec APIs at once. The main gain is that this simplifies autoprobing a lot. Before this change, it could happen that the VO loaded the "wrong" hwdec API, and the decoder was stuck with the choice (breaking hw decoding). With the change applied, the VO simply loads all available APIs, so autoprobing trickery is left entirely to the decoder. In the past, we were quite careful about not accidentally loading the wrong interop drivers. This was in part to make sure autoprobing works, but also because libva had this obnoxious bug of dumping garbage to stderr when using the API. libva was fixed, so this is not a problem anymore. The --opengl-hwdec-interop option is changed in various ways (again...), and renamed to --gpu-hwdec-interop. It does not have much use anymore, other than debugging. It's notable that the order in the hwdec interop array ra_hwdec_drivers[] still matters if multiple drivers support the same image formats, so the option can explicitly force one, if that should ever be necessary, or more likely, for debugging. One example are the ra_hwdec_d3d11egl and ra_hwdec_d3d11eglrgb drivers, which both support d3d11 input. vo_gpu now always loads the interop lazily by default, but when it does, it loads them all. vo_opengl_cb now always loads them when the GL context handle is initialized. I don't expect that this causes any problems. It's now possible to do things like changing between vdpau and nvdec decoding at runtime. This is also preparation for cleaning up vd_lavc.c hwdec autoprobing. It's another reason why hwdec_devices_request_all() does not take a hwdec type anymore.
2017-12-01 04:05:00 +00:00
MP_TARRAY_APPEND(devs, devs->hwctxs, devs->num_hwctxs, ctx);
pthread_mutex_unlock(&devs->lock);
}
void hwdec_devices_remove(struct mp_hwdec_devices *devs, struct mp_hwdec_ctx *ctx)
{
pthread_mutex_lock(&devs->lock);
vo_gpu: make it possible to load multiple hwdec interop drivers Make the VO<->decoder interface capable of supporting multiple hwdec APIs at once. The main gain is that this simplifies autoprobing a lot. Before this change, it could happen that the VO loaded the "wrong" hwdec API, and the decoder was stuck with the choice (breaking hw decoding). With the change applied, the VO simply loads all available APIs, so autoprobing trickery is left entirely to the decoder. In the past, we were quite careful about not accidentally loading the wrong interop drivers. This was in part to make sure autoprobing works, but also because libva had this obnoxious bug of dumping garbage to stderr when using the API. libva was fixed, so this is not a problem anymore. The --opengl-hwdec-interop option is changed in various ways (again...), and renamed to --gpu-hwdec-interop. It does not have much use anymore, other than debugging. It's notable that the order in the hwdec interop array ra_hwdec_drivers[] still matters if multiple drivers support the same image formats, so the option can explicitly force one, if that should ever be necessary, or more likely, for debugging. One example are the ra_hwdec_d3d11egl and ra_hwdec_d3d11eglrgb drivers, which both support d3d11 input. vo_gpu now always loads the interop lazily by default, but when it does, it loads them all. vo_opengl_cb now always loads them when the GL context handle is initialized. I don't expect that this causes any problems. It's now possible to do things like changing between vdpau and nvdec decoding at runtime. This is also preparation for cleaning up vd_lavc.c hwdec autoprobing. It's another reason why hwdec_devices_request_all() does not take a hwdec type anymore.
2017-12-01 04:05:00 +00:00
for (int n = 0; n < devs->num_hwctxs; n++) {
if (devs->hwctxs[n] == ctx) {
MP_TARRAY_REMOVE_AT(devs->hwctxs, devs->num_hwctxs, n);
break;
}
}
pthread_mutex_unlock(&devs->lock);
}
void hwdec_devices_set_loader(struct mp_hwdec_devices *devs,
void (*load_api)(void *ctx, int imgfmt), void *load_api_ctx)
{
devs->load_api = load_api;
devs->load_api_ctx = load_api_ctx;
}
void hwdec_devices_request_for_img_fmt(struct mp_hwdec_devices *devs, int imgfmt)
{
if (devs->load_api && !hwdec_devices_get_first(devs))
devs->load_api(devs->load_api_ctx, imgfmt);
}
vo_gpu: make it possible to load multiple hwdec interop drivers Make the VO<->decoder interface capable of supporting multiple hwdec APIs at once. The main gain is that this simplifies autoprobing a lot. Before this change, it could happen that the VO loaded the "wrong" hwdec API, and the decoder was stuck with the choice (breaking hw decoding). With the change applied, the VO simply loads all available APIs, so autoprobing trickery is left entirely to the decoder. In the past, we were quite careful about not accidentally loading the wrong interop drivers. This was in part to make sure autoprobing works, but also because libva had this obnoxious bug of dumping garbage to stderr when using the API. libva was fixed, so this is not a problem anymore. The --opengl-hwdec-interop option is changed in various ways (again...), and renamed to --gpu-hwdec-interop. It does not have much use anymore, other than debugging. It's notable that the order in the hwdec interop array ra_hwdec_drivers[] still matters if multiple drivers support the same image formats, so the option can explicitly force one, if that should ever be necessary, or more likely, for debugging. One example are the ra_hwdec_d3d11egl and ra_hwdec_d3d11eglrgb drivers, which both support d3d11 input. vo_gpu now always loads the interop lazily by default, but when it does, it loads them all. vo_opengl_cb now always loads them when the GL context handle is initialized. I don't expect that this causes any problems. It's now possible to do things like changing between vdpau and nvdec decoding at runtime. This is also preparation for cleaning up vd_lavc.c hwdec autoprobing. It's another reason why hwdec_devices_request_all() does not take a hwdec type anymore.
2017-12-01 04:05:00 +00:00
char *hwdec_devices_get_names(struct mp_hwdec_devices *devs)
{
char *res = NULL;
for (int n = 0; n < devs->num_hwctxs; n++) {
if (res)
ta_xstrdup_append(&res, ",");
ta_xstrdup_append(&res, devs->hwctxs[n]->driver_name);
}
return res;
}
static const struct hwcontext_fns *const hwcontext_fns[] = {
#if HAVE_CUDA_HWACCEL
&hwcontext_fns_cuda,
#endif
#if HAVE_D3D_HWACCEL
&hwcontext_fns_d3d11,
#endif
#if HAVE_D3D9_HWACCEL
&hwcontext_fns_dxva2,
#endif
#if HAVE_VAAPI
&hwcontext_fns_vaapi,
#endif
#if HAVE_VDPAU
&hwcontext_fns_vdpau,
#endif
NULL,
};
const struct hwcontext_fns *hwdec_get_hwcontext_fns(int av_hwdevice_type)
{
for (int n = 0; hwcontext_fns[n]; n++) {
if (hwcontext_fns[n]->av_hwdevice_type == av_hwdevice_type)
return hwcontext_fns[n];
}
return NULL;
}