diff --git a/app/CMakeLists.txt b/app/CMakeLists.txt
index 143065b..cbf3cc5 100644
--- a/app/CMakeLists.txt
+++ b/app/CMakeLists.txt
@@ -24,6 +24,7 @@ add_library( # Sets the name of the library.
             src/main/cpp/ffmpeg/ffmpeg_opt.c
             src/main/cpp/ffmpeg_cmd.c
             src/main/cpp/ffmpeg/ffprobe.c
+            src/main/cpp/ffmpeg/ffmpeg_hw.c
             src/main/cpp/audio_player.c
             src/main/cpp/openSL_audio_player.c
             src/main/cpp/video_player.c
diff --git a/app/src/main/cpp/ffmpeg/ffmpeg_hw.c b/app/src/main/cpp/ffmpeg/ffmpeg_hw.c
new file mode 100644
index 0000000..962d8f7
--- /dev/null
+++ b/app/src/main/cpp/ffmpeg/ffmpeg_hw.c
@@ -0,0 +1,482 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <string.h>
+
+#include "libavutil/avstring.h"
+
+#include "ffmpeg.h"
+
+static int nb_hw_devices;
+static HWDevice **hw_devices;
+
+static HWDevice *hw_device_get_by_type(enum AVHWDeviceType type)
+{
+    HWDevice *found = NULL;
+    int i;
+    for (i = 0; i < nb_hw_devices; i++) {
+        if (hw_devices[i]->type == type) {
+            if (found)
+                return NULL;
+            found = hw_devices[i];
+        }
+    }
+    return found;
+}
+
+HWDevice *hw_device_get_by_name(const char *name)
+{
+    int i;
+    for (i = 0; i < nb_hw_devices; i++) {
+        if (!strcmp(hw_devices[i]->name, name))
+            return hw_devices[i];
+    }
+    return NULL;
+}
+
+static HWDevice *hw_device_add(void)
+{
+    int err;
+    err = av_reallocp_array(&hw_devices, nb_hw_devices + 1,
+                            sizeof(*hw_devices));
+    if (err) {
+        nb_hw_devices = 0;
+        return NULL;
+    }
+    hw_devices[nb_hw_devices] = av_mallocz(sizeof(HWDevice));
+    if (!hw_devices[nb_hw_devices])
+        return NULL;
+    return hw_devices[nb_hw_devices++];
+}
+
+static char *hw_device_default_name(enum AVHWDeviceType type)
+{
+    // Make an automatic name of the form "type%d".  We arbitrarily
+    // limit at 1000 anonymous devices of the same type - there is
+    // probably something else very wrong if you get to this limit.
+    const char *type_name = av_hwdevice_get_type_name(type);
+    char *name;
+    size_t index_pos;
+    int index, index_limit = 1000;
+    index_pos = strlen(type_name);
+    name = av_malloc(index_pos + 4);
+    if (!name)
+        return NULL;
+    for (index = 0; index < index_limit; index++) {
+        snprintf(name, index_pos + 4, "%s%d", type_name, index);
+        if (!hw_device_get_by_name(name))
+            break;
+    }
+    if (index >= index_limit) {
+        av_freep(&name);
+        return NULL;
+    }
+    return name;
+}
+
+int hw_device_init_from_string(const char *arg, HWDevice **dev_out)
+{
+    // "type=name:device,key=value,key2=value2"
+    // "type:device,key=value,key2=value2"
+    // -> av_hwdevice_ctx_create()
+    // "type=name@name"
+    // "type@name"
+    // -> av_hwdevice_ctx_create_derived()
+
+    AVDictionary *options = NULL;
+    const char *type_name = NULL, *name = NULL, *device = NULL;
+    enum AVHWDeviceType type;
+    HWDevice *dev, *src;
+    AVBufferRef *device_ref = NULL;
+    int err;
+    const char *errmsg, *p, *q;
+    size_t k;
+
+    k = strcspn(arg, ":=@");
+    p = arg + k;
+
+    type_name = av_strndup(arg, k);
+    if (!type_name) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+    type = av_hwdevice_find_type_by_name(type_name);
+    if (type == AV_HWDEVICE_TYPE_NONE) {
+        errmsg = "unknown device type";
+        goto invalid;
+    }
+
+    if (*p == '=') {
+        k = strcspn(p + 1, ":@");
+
+        name = av_strndup(p + 1, k);
+        if (!name) {
+            err = AVERROR(ENOMEM);
+            goto fail;
+        }
+        if (hw_device_get_by_name(name)) {
+            errmsg = "named device already exists";
+            goto invalid;
+        }
+
+        p += 1 + k;
+    } else {
+        name = hw_device_default_name(type);
+        if (!name) {
+            err = AVERROR(ENOMEM);
+            goto fail;
+        }
+    }
+
+    if (!*p) {
+        // New device with no parameters.
+        err = av_hwdevice_ctx_create(&device_ref, type,
+                                     NULL, NULL, 0);
+        if (err < 0)
+            goto fail;
+
+    } else if (*p == ':') {
+        // New device with some parameters.
+        ++p;
+        q = strchr(p, ',');
+        if (q) {
+            if (q - p > 0) {
+                device = av_strndup(p, q - p);
+                if (!device) {
+                    err = AVERROR(ENOMEM);
+                    goto fail;
+                }
+            }
+            err = av_dict_parse_string(&options, q + 1, "=", ",", 0);
+            if (err < 0) {
+                errmsg = "failed to parse options";
+                goto invalid;
+            }
+        }
+
+        err = av_hwdevice_ctx_create(&device_ref, type,
+                                     q ? device : p[0] ? p : NULL,
+                                     options, 0);
+        if (err < 0)
+            goto fail;
+
+    } else if (*p == '@') {
+        // Derive from existing device.
+
+        src = hw_device_get_by_name(p + 1);
+        if (!src) {
+            errmsg = "invalid source device name";
+            goto invalid;
+        }
+
+        err = av_hwdevice_ctx_create_derived(&device_ref, type,
+                                             src->device_ref, 0);
+        if (err < 0)
+            goto fail;
+    } else {
+        errmsg = "parse error";
+        goto invalid;
+    }
+
+    dev = hw_device_add();
+    if (!dev) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    dev->name = name;
+    dev->type = type;
+    dev->device_ref = device_ref;
+
+    if (dev_out)
+        *dev_out = dev;
+
+    name = NULL;
+    err = 0;
+done:
+    av_freep(&type_name);
+    av_freep(&name);
+    av_freep(&device);
+    av_dict_free(&options);
+    return err;
+invalid:
+    av_log(NULL, AV_LOG_ERROR,
+           "Invalid device specification \"%s\": %s\n", arg, errmsg);
+    err = AVERROR(EINVAL);
+    goto done;
+fail:
+    av_log(NULL, AV_LOG_ERROR,
+           "Device creation failed: %d.\n", err);
+    av_buffer_unref(&device_ref);
+    goto done;
+}
+
+static int hw_device_init_from_type(enum AVHWDeviceType type,
+                                    const char *device,
+                                    HWDevice **dev_out)
+{
+    AVBufferRef *device_ref = NULL;
+    HWDevice *dev;
+    char *name;
+    int err;
+
+    name = hw_device_default_name(type);
+    if (!name) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    err = av_hwdevice_ctx_create(&device_ref, type, device, NULL, 0);
+    if (err < 0) {
+        av_log(NULL, AV_LOG_ERROR,
+               "Device creation failed: %d.\n", err);
+        goto fail;
+    }
+
+    dev = hw_device_add();
+    if (!dev) {
+        err = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    dev->name = name;
+    dev->type = type;
+    dev->device_ref = device_ref;
+
+    if (dev_out)
+        *dev_out = dev;
+
+    return 0;
+
+fail:
+    av_freep(&name);
+    av_buffer_unref(&device_ref);
+    return err;
+}
+
+void hw_device_free_all(void)
+{
+    int i;
+    for (i = 0; i < nb_hw_devices; i++) {
+        av_freep(&hw_devices[i]->name);
+        av_buffer_unref(&hw_devices[i]->device_ref);
+        av_freep(&hw_devices[i]);
+    }
+    av_freep(&hw_devices);
+    nb_hw_devices = 0;
+}
+
+static HWDevice *hw_device_match_by_codec(const AVCodec *codec)
+{
+    const AVCodecHWConfig *config;
+    HWDevice *dev;
+    int i;
+    for (i = 0;; i++) {
+        config = avcodec_get_hw_config(codec, i);
+        if (!config)
+            return NULL;
+        if (!(config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX))
+            continue;
+        dev = hw_device_get_by_type(config->device_type);
+        if (dev)
+            return dev;
+    }
+}
+
+int hw_device_setup_for_decode(InputStream *ist)
+{
+    const AVCodecHWConfig *config;
+    enum AVHWDeviceType type;
+    HWDevice *dev = NULL;
+    int err, auto_device = 0;
+
+    if (ist->hwaccel_device) {
+        dev = hw_device_get_by_name(ist->hwaccel_device);
+        if (!dev) {
+            if (ist->hwaccel_id == HWACCEL_AUTO) {
+                auto_device = 1;
+            } else if (ist->hwaccel_id == HWACCEL_GENERIC) {
+                type = ist->hwaccel_device_type;
+                err = hw_device_init_from_type(type, ist->hwaccel_device,
+                                               &dev);
+            } else {
+                // This will be dealt with by API-specific initialisation
+                // (using hwaccel_device), so nothing further needed here.
+                return 0;
+            }
+        } else {
+            if (ist->hwaccel_id == HWACCEL_AUTO) {
+                ist->hwaccel_device_type = dev->type;
+            } else if (ist->hwaccel_device_type != dev->type) {
+                av_log(ist->dec_ctx, AV_LOG_ERROR, "Invalid hwaccel device "
+                       "specified for decoder: device %s of type %s is not "
+                       "usable with hwaccel %s.\n", dev->name,
+                       av_hwdevice_get_type_name(dev->type),
+                       av_hwdevice_get_type_name(ist->hwaccel_device_type));
+                return AVERROR(EINVAL);
+            }
+        }
+    } else {
+        if (ist->hwaccel_id == HWACCEL_AUTO) {
+            auto_device = 1;
+        } else if (ist->hwaccel_id == HWACCEL_GENERIC) {
+            type = ist->hwaccel_device_type;
+            dev = hw_device_get_by_type(type);
+            if (!dev)
+                err = hw_device_init_from_type(type, NULL, &dev);
+        } else {
+            dev = hw_device_match_by_codec(ist->dec);
+            if (!dev) {
+                // No device for this codec, but not using generic hwaccel
+                // and therefore may well not need one - ignore.
+                return 0;
+            }
+        }
+    }
+
+    if (auto_device) {
+        int i;
+        if (!avcodec_get_hw_config(ist->dec, 0)) {
+            // Decoder does not support any hardware devices.
+            return 0;
+        }
+        for (i = 0; !dev; i++) {
+            config = avcodec_get_hw_config(ist->dec, i);
+            if (!config)
+                break;
+            type = config->device_type;
+            dev = hw_device_get_by_type(type);
+            if (dev) {
+                av_log(ist->dec_ctx, AV_LOG_INFO, "Using auto "
+                       "hwaccel type %s with existing device %s.\n",
+                       av_hwdevice_get_type_name(type), dev->name);
+            }
+        }
+        for (i = 0; !dev; i++) {
+            config = avcodec_get_hw_config(ist->dec, i);
+            if (!config)
+                break;
+            type = config->device_type;
+            // Try to make a new device of this type.
+            err = hw_device_init_from_type(type, ist->hwaccel_device,
+                                           &dev);
+            if (err < 0) {
+                // Can't make a device of this type.
+                continue;
+            }
+            if (ist->hwaccel_device) {
+                av_log(ist->dec_ctx, AV_LOG_INFO, "Using auto "
+                       "hwaccel type %s with new device created "
+                       "from %s.\n", av_hwdevice_get_type_name(type),
+                       ist->hwaccel_device);
+            } else {
+                av_log(ist->dec_ctx, AV_LOG_INFO, "Using auto "
+                       "hwaccel type %s with new default device.\n",
+                       av_hwdevice_get_type_name(type));
+            }
+        }
+        if (dev) {
+            ist->hwaccel_device_type = type;
+        } else {
+            av_log(ist->dec_ctx, AV_LOG_INFO, "Auto hwaccel "
+                   "disabled: no device found.\n");
+            ist->hwaccel_id = HWACCEL_NONE;
+            return 0;
+        }
+    }
+
+    if (!dev) {
+        av_log(ist->dec_ctx, AV_LOG_ERROR, "No device available "
+               "for decoder: device type %s needed for codec %s.\n",
+               av_hwdevice_get_type_name(type), ist->dec->name);
+        return err;
+    }
+
+    ist->dec_ctx->hw_device_ctx = av_buffer_ref(dev->device_ref);
+    if (!ist->dec_ctx->hw_device_ctx)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+int hw_device_setup_for_encode(OutputStream *ost)
+{
+    HWDevice *dev;
+
+    dev = hw_device_match_by_codec(ost->enc);
+    if (dev) {
+        ost->enc_ctx->hw_device_ctx = av_buffer_ref(dev->device_ref);
+        if (!ost->enc_ctx->hw_device_ctx)
+            return AVERROR(ENOMEM);
+        return 0;
+    } else {
+        // No device required, or no device available.
+        return 0;
+    }
+}
+
+static int hwaccel_retrieve_data(AVCodecContext *avctx, AVFrame *input)
+{
+    InputStream *ist = avctx->opaque;
+    AVFrame *output = NULL;
+    enum AVPixelFormat output_format = ist->hwaccel_output_format;
+    int err;
+
+    if (input->format == output_format) {
+        // Nothing to do.
+        return 0;
+    }
+
+    output = av_frame_alloc();
+    if (!output)
+        return AVERROR(ENOMEM);
+
+    output->format = output_format;
+
+    err = av_hwframe_transfer_data(output, input, 0);
+    if (err < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Failed to transfer data to "
+               "output frame: %d.\n", err);
+        goto fail;
+    }
+
+    err = av_frame_copy_props(output, input);
+    if (err < 0) {
+        av_frame_unref(output);
+        goto fail;
+    }
+
+    av_frame_unref(input);
+    av_frame_move_ref(input, output);
+    av_frame_free(&output);
+
+    return 0;
+
+fail:
+    av_frame_free(&output);
+    return err;
+}
+
+int hwaccel_decode_init(AVCodecContext *avctx)
+{
+    InputStream *ist = avctx->opaque;
+
+    ist->hwaccel_retrieve_data = &hwaccel_retrieve_data;
+
+    return 0;
+}