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, 103 insertions, 0 deletions

diff --git a/libavcodec/v4l2_m2m.h b/libavcodec/v4l2_m2m.h
new file mode 100644
index 0000000..13e2285
--- /dev/null
+++ b/libavcodec/v4l2_m2m.h
@@ -0,0 +1,103 @@
+/*
+ * V4L2 mem2mem 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_M2M_H
+#define AVCODEC_V4L2_M2M_H
+
+#include <semaphore.h>
+#include <unistd.h>
+#include <dirent.h>
+#include "libavcodec/avcodec.h"
+#include "v4l2_context.h"
+
+#define container_of(ptr, type, member) ({ \
+        const __typeof__(((type *)0)->member ) *__mptr = (ptr); \
+        (type *)((char *)__mptr - offsetof(type,member) );})
+
+#define V4L_M2M_DEFAULT_OPTS \
+    { "num_output_buffers", "Number of buffers in the output context",\
+        OFFSET(output.num_buffers), AV_OPT_TYPE_INT, { .i64 = 16 }, 6, INT_MAX, FLAGS }
+
+typedef struct V4L2m2mContext
+{
+    AVClass *class;
+    char devname[PATH_MAX];
+    int fd;
+
+    /* the codec context queues */
+    V4L2Context capture;
+    V4L2Context output;
+
+    /* refcount of buffers held by the user */
+    atomic_uint refcount;
+
+    /* dynamic stream reconfig */
+    AVCodecContext *avctx;
+    sem_t refsync;
+    int reinit;
+
+    /* null frame/packet received */
+    int draining;
+} V4L2m2mContext;
+
+/**
+ * Probes the video nodes looking for the required codec capabilities.
+ *
+ * @param[in] ctx The AVCodecContext instantiated by the encoder/decoder.
+ *
+ * @returns 0 if a driver is found, a negative number otherwise.
+ */
+int ff_v4l2_m2m_codec_init(AVCodecContext *avctx);
+
+/**
+ * Releases all the codec resources if all AVBufferRefs have been returned to the
+ * ctx. Otherwise keep the driver open.
+ *
+ * @param[in] The AVCodecContext instantiated by the encoder/decoder.
+ *
+ * @returns 0
+ *
+ */
+int ff_v4l2_m2m_codec_end(AVCodecContext *avctx);
+
+/**
+ * Reinitializes the V4L2m2mContext when the driver cant continue processing
+ * with the capture parameters.
+ *
+ * @param[in] ctx The V4L2m2mContext instantiated by the encoder/decoder.
+ *
+ * @returns 0 in case of success, negative number otherwise
+ */
+int ff_v4l2_m2m_codec_reinit(V4L2m2mContext *ctx);
+
+/**
+ * Reinitializes the V4L2m2mContext when the driver cant continue processing
+ * with the  any of the current V4L2Contexts (ie, changes in output and capture).
+ *
+ * @param[in] ctx The V4L2m2mContext instantiated by the encoder/decoder.
+ *
+ * @returns 0 in case of success, negative number otherwise
+ */
+int ff_v4l2_m2m_codec_full_reinit(V4L2m2mContext *ctx);
+
+#endif /* AVCODEC_V4L2_M2M_H */