libavcodec: v4l2: add support for v4l2 mem2mem codecs

    This patchset enhances Alexis Ballier's original patch and validates
    it using Qualcomm's Venus hardware (driver recently landed upstream
    [1]).

    This has been tested on Qualcomm's DragonBoard 410c and 820c
    Configure/make scripts have been validated on Ubuntu 10.04 and
    16.04.

    Tested decoders:
           - h264
           - h263
           - mpeg4
           - vp8
           - vp9
           - hevc

    Tested encoders:
           - h264
           - h263
           - mpeg4

    Tested transcoding (concurrent encoding/decoding)

    Some of the changes introduced:
        - v4l2: code cleanup and abstractions added
        - v4l2: follow the new encode/decode api.
        - v4l2: fix display size for NV12 output pool.
        - v4l2: handle EOS (EPIPE and draining)
        - v4l2: vp8 and mpeg4 decoding and encoding.
        - v4l2: hevc and vp9 support.
        - v4l2: generate EOF on dequeue errors.
        - v4l2: h264_mp4toannexb filtering.
        - v4l2: fixed make install and fate issues.
        - v4l2: codecs enabled/disabled depending on pixfmt defined
        - v4l2: pass timebase/framerate to the context
        - v4l2: runtime decoder reconfiguration.
        - v4l2: add more frame information
        - v4l2: free hardware resources on last reference being released
        - v4l2: encoding: disable b-frames for upstreaming (patch required)

    [1] https://lwn.net/Articles/697956/

    System Level view:
        v42l_m2m_enc/dec --> v4l2_m2m --> v4l2_context --> v4l2_buffers

    Reviewed-by: Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
    Reviewed-by: Alexis Ballier <aballier@gentoo.org>
    Tested-by: Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>

Signed-off-by: wm4 <nfxjfg@googlemail.com>

1 files changed, 181 insertions, 0 deletions

diff --git a/libavcodec/v4l2_context.h b/libavcodec/v4l2_context.h
new file mode 100644
index 0000000000..b6667a04e3
--- /dev/null
+++ b/libavcodec/v4l2_context.h
@@ -0,0 +1,181 @@
+/*
+ * V4L2 context helper functions.
+ *
+ * Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
+ * Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
+ *
+ * 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
+ */
+
+#ifndef AVCODEC_V4L2_CONTEXT_H
+#define AVCODEC_V4L2_CONTEXT_H
+
+#include <stdatomic.h>
+#include "libavcodec/avcodec.h"
+#include "libavutil/pixfmt.h"
+#include "libavutil/frame.h"
+#include "libavutil/buffer.h"
+#include "v4l2_buffers.h"
+
+typedef struct V4L2Context {
+    /**
+     * context name.
+     */
+    const char* name;
+
+    /**
+     * Type of this buffer context.
+     * See V4L2_BUF_TYPE_VIDEO_* in videodev2.h
+     * Readonly after init.
+     */
+    enum v4l2_buf_type type;
+
+    /**
+     * AVPixelFormat corresponding to this buffer context.
+     * AV_PIX_FMT_NONE means this is an encoded stream.
+     */
+    enum AVPixelFormat av_pix_fmt;
+
+    /**
+     * AVCodecID corresponding to this buffer context.
+     * AV_CODEC_ID_RAWVIDEO means this is a raw stream and av_pix_fmt must be set to a valid value.
+     */
+    enum AVCodecID av_codec_id;
+
+    /**
+     * Format returned by the driver after initializing the buffer context.
+     * Readonly after init.
+     */
+    struct v4l2_format format;
+
+    /**
+     * Width and height of the frames it produces (in case of a capture context, e.g. when decoding)
+     * or accepts (in case of an output context, e.g. when encoding).
+     */
+    int width, height;
+
+    /**
+     * Indexed array of V4L2Buffers
+     */
+    V4L2Buffer *buffers;
+
+    /**
+     * Readonly after init.
+     */
+    int num_buffers;
+
+    /**
+     * Whether the stream has been started (VIDIOC_STREAMON has been sent).
+     */
+    int streamon;
+
+    /**
+     *  Either no more buffers available or an unrecoverable error was notified
+     *  by the V4L2 kernel driver: once set the context has to be exited.
+     */
+    int done;
+
+} V4L2Context;
+
+/**
+ * Initializes a V4L2Context.
+ *
+ * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
+ * @return 0 in case of success, a negative value representing the error otherwise.
+ */
+int ff_v4l2_context_init(V4L2Context* ctx);
+
+/**
+ * Sets the V4L2Context format in the v4l2 driver.
+ *
+ * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
+ * @return 0 in case of success, a negative value representing the error otherwise.
+ */
+int ff_v4l2_context_set_format(V4L2Context* ctx);
+
+/**
+ * Queries the driver for a valid v4l2 format and copies it to the context.
+ *
+ * @param[in] ctx A pointer to a V4L2Context. See V4L2Context description for required variables.
+ * @return 0 in case of success, a negative value representing the error otherwise.
+ */
+int ff_v4l2_context_get_format(V4L2Context* ctx);
+
+/**
+ * Releases a V4L2Context.
+ *
+ * @param[in] ctx A pointer to a V4L2Context.
+ *               The caller is reponsible for freeing it.
+ *               It must not be used after calling this function.
+ */
+void ff_v4l2_context_release(V4L2Context* ctx);
+
+/**
+ * Sets the status of a V4L2Context.
+ *
+ * @param[in] ctx A pointer to a V4L2Context.
+ * @param[in] cmd The status to set (VIDIOC_STREAMON or VIDIOC_STREAMOFF).
+ *                Warning: If VIDIOC_STREAMOFF is sent to a buffer context that still has some frames buffered,
+ *                those frames will be dropped.
+ * @return 0 in case of success, a negative value representing the error otherwise.
+ */
+int ff_v4l2_context_set_status(V4L2Context* ctx, int cmd);
+
+/**
+ * Dequeues a buffer from a V4L2Context to an AVPacket.
+ *
+ * The pkt must be non NULL.
+ * @param[in] ctx The V4L2Context to dequeue from.
+ * @param[inout] pkt The AVPacket to dequeue to.
+ * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
+ */
+int ff_v4l2_context_dequeue_packet(V4L2Context* ctx, AVPacket* pkt);
+
+/**
+ * Dequeues a buffer from a V4L2Context to an AVFrame.
+ *
+ * The frame must be non NULL.
+ * @param[in] ctx The V4L2Context to dequeue from.
+ * @param[inout] f The AVFrame to dequeue to.
+ * @return 0 in case of success, AVERROR(EAGAIN) if no buffer was ready, another negative error in case of error.
+ */
+int ff_v4l2_context_dequeue_frame(V4L2Context* ctx, AVFrame* f);
+
+/**
+ * Enqueues a buffer to a V4L2Context from an AVPacket
+ *
+ * The packet must be non NULL.
+ * When the size of the pkt is null, the buffer is not queued but a V4L2_DEC_CMD_STOP command is sent instead to the driver.
+ *
+ * @param[in] ctx The V4L2Context to enqueue to.
+ * @param[in] pkt A pointer to an AVPacket.
+ * @return 0 in case of success, a negative error otherwise.
+ */
+int ff_v4l2_context_enqueue_packet(V4L2Context* ctx, const AVPacket* pkt);
+
+/**
+ * Enqueues a buffer to a V4L2Context from an AVFrame
+ *
+ * The frame must be non NULL.
+ *
+ * @param[in] ctx The V4L2Context to enqueue to.
+ * @param[in] f A pointer to an AVFrame to enqueue.
+ * @return 0 in case of success, a negative error otherwise.
+ */
+int ff_v4l2_context_enqueue_frame(V4L2Context* ctx, const AVFrame* f);
+
+#endif // AVCODEC_V4L2_CONTEXT_H