+static AVHWAccel *find_hwaccel(enum AVCodecID codec_id,
+ enum AVPixelFormat pix_fmt)
+{
+ AVHWAccel *hwaccel = NULL;
+
+ while ((hwaccel = av_hwaccel_next(hwaccel)))
+ if (hwaccel->id == codec_id
+ && hwaccel->pix_fmt == pix_fmt)
+ return hwaccel;
+ return NULL;
+}
+
+static int setup_hwaccel(AVCodecContext *avctx,
+ const enum AVPixelFormat fmt,
+ const char *name)
+{
+ AVHWAccel *hwa = find_hwaccel(avctx->codec_id, fmt);
+ int ret = 0;
+
+ if (!hwa) {
+ av_log(avctx, AV_LOG_ERROR,
+ "Could not find an AVHWAccel for the pixel format: %s",
+ name);
+ return AVERROR(ENOENT);
+ }
+
+ if (hwa->priv_data_size) {
+ avctx->internal->hwaccel_priv_data = av_mallocz(hwa->priv_data_size);
+ if (!avctx->internal->hwaccel_priv_data)
+ return AVERROR(ENOMEM);
+ }
+
+ if (hwa->init) {
+ ret = hwa->init(avctx);
+ if (ret < 0) {
+ av_freep(&avctx->internal->hwaccel_priv_data);
+ return ret;
+ }
+ }
+
+ avctx->hwaccel = hwa;
+
+ return 0;
+}
+
+int ff_get_format(AVCodecContext *avctx, const enum AVPixelFormat *fmt)
+{
+ const AVPixFmtDescriptor *desc;
+ enum AVPixelFormat *choices;
+ enum AVPixelFormat ret;
+ unsigned n = 0;
+
+ while (fmt[n] != AV_PIX_FMT_NONE)
+ ++n;
+
+ choices = av_malloc_array(n + 1, sizeof(*choices));
+ if (!choices)
+ return AV_PIX_FMT_NONE;
+
+ memcpy(choices, fmt, (n + 1) * sizeof(*choices));
+
+ for (;;) {
+ ret = avctx->get_format(avctx, choices);
+
+ desc = av_pix_fmt_desc_get(ret);
+ if (!desc) {
+ ret = AV_PIX_FMT_NONE;
+ break;
+ }
+
+ if (avctx->hwaccel && avctx->hwaccel->uninit)
+ avctx->hwaccel->uninit(avctx);
+ av_freep(&avctx->internal->hwaccel_priv_data);
+ avctx->hwaccel = NULL;
+
+ if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL))
+ break;
+
+ if (!setup_hwaccel(avctx, ret, desc->name))
+ break;
+
+ /* Remove failed hwaccel from choices */
+ for (n = 0; choices[n] != ret; n++)
+ av_assert0(choices[n] != AV_PIX_FMT_NONE);
+
+ do
+ choices[n] = choices[n + 1];
+ while (choices[n++] != AV_PIX_FMT_NONE);
+ }
+
+ av_freep(&choices);
+ return ret;
+}
+