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Sur d’autres sites (14345)

Android Java — Using and building FFMPEG library in Android Studio(Cmake)

12 septembre 2017, par y3k00000

As title, I’m trying to use the ffmpeg source code as library in Android Studio on Ubuntu Linux, but meeting some trouble in compilation stage. I think I must be missing some compile option but having no idea what I miss, can somebody lend a hand ?

My codes & settings are below :

A simple auto-generated .cpp

#include 

#include <string>

#include "libavcodec/aacenc.h"



extern "C"

JNIEXPORT jstring JNICALL

Java_y3k_testffmpegnative_MainActivity_stringFromJNI(

        JNIEnv *env,

        jobject /* this */) {

    std::string hello = "Hello from C++";

    return env->NewStringUTF(hello.c_str());

}



AACEncContext * aacEncContext; // Just trying by adding this.

</string>

I’ve tried these Gradle setting and it didn’t help :

android {

    ....

    externalNativeBuild {

        cmake {

            arguments "-DANDROID_TOOLCHAIN=clang"

            cFlags "-std=c99"

            cppFlags "-frtti","-fexceptions"

        }

    }

}

....

CMakeLists.txt

(Android Studio generated)

....

include_directories( /home/y3k/ffmpeg )

Error message while compiling :

/home/y3k/ffmpeg/libavutil/float_dsp.h

Error:(164, 50) error: expected ')'

Information:(164, 30) to match this '('

Error:(164, 50) error: expected ')'

Information:(164, 30) note: to match this '('

/home/y3k/ffmpeg/libavutil/fixed_dsp.h

Error:(153, 44) error: expected ')'

Information:(153, 30) to match this '('

Error:(153, 44) error: expected ')'

Information:(153, 30) note: to match this '('

/home/y3k/ffmpeg/libavcodec/mpeg4audio.h

Error:(44, 8) error: unknown type name 'av_export'

Error:(44, 18) error: expected unqualified-id

Error:(44, 8) error: unknown type name 'av_export'

Error:(44, 18) error: expected unqualified-id

/home/y3k/ffmpeg/libavcodec/aac.h

Error:(294, 21) error: expected member name or ';' after declaration specifiers

Error:(294, 21) error: expected member name or ';' after declaration specifiers

FFMpeg config.h generated by this script :

NDK=/home/y3k/Android/Sdk/ndk-bundle

SYSROOT=$NDK/platforms/android-23/arch-arm/

TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64

function build_one

{

./configure \

 --prefix=$PREFIX \

 --disable-shared \

 --enable-static \

 --disable-doc \

 --disable-ffmpeg \

 --disable-ffplay \

 --disable-ffprobe \

 --disable-ffserver \

 --disable-avdevice \

 --disable-doc \

 --disable-symver \

 --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \

 --target-os=linux \

 --arch=arm \

 --enable-cross-compile \

 --sysroot=$SYSROOT \

 --extra-cflags="-Os -fpic $ADDI_CFLAGS" \

 --extra-ldflags="$ADDI_LDFLAGS" \

 $ADDITIONAL_CONFIGURE_FLAG

make clean

make

make install

}

CPU=arm

PREFIX=$(pwd)/android/$CPU

ADDI_CFLAGS="-marm"

build_one

By tracing the errors I found these lines :

in float_dsp.h, fixed_dsp.h :

void (*butterflies_float)(float *av_restrict v1, float *av_restrict v2, int len);

av_restrict defined in config.h

#define av_restrict restrict

in aac.h :

....

struct AACContext {

    AVClass        *class;

....

in mpeg4audio.h :

extern av_export const int avpriv_mpeg4audio_sample_rates[16];

So I’m guessing it’s because the compiler misrecognized the C code as C++, I tried adding these :

arguments "-DANDROID_TOOLCHAIN=clang"

cFlags "-std=c99"

to my build.gradle but didn’t help. Having no idea where to move on. :(

I’m using the latest stable version of Android Studio on Ubuntu desktop. Please don’t be hesitate to ask if any extra information is required.

Also I’ve been tried edit my native-lib.cpp into .c (Surely with the code contents changed), but wasn’t working either.

Appreciate for any help.

How to send ffmpeg AVPacket through WebRTC (using libdatachannel)

14 novembre 2022, par mike
I'm encoding a video frame with the ffmpeg libraries, generating an AVPacket with compressed data.




Thanks to some recent advice here on S/O, I am trying to send that frame over a network using the WebRTC library libdatachannel, specifically by adapting the example here :




https://github.com/paullouisageneau/libdatachannel/tree/master/examples/streamer




I am seeing problems inside h264rtppacketizer.cpp (part of the library, not the example) which are almost certainly to do with how I'm providing the sample data.
(I don't think that this is anything to do with libdatachannel specifically, it will be an issue with what I'm sending)




The example code reads each encoded frame from a file, and populates a sample by setting the content of the file to the contents of the file :




sample = *reinterpret_cast *>(&fileContents);




sample is just a std::vector<byte>;</byte>




I have naively copied the contents of an AVPacket->data pointer into the sample vector :



```
sample.resize(pkt->size);&#xA;memcpy(sample.data(), pkt->data, pkt->size * sizeof(std::byte));    &#xA;
```



but the packetizer is falling over when trying to get length values out of that data.
Specifically, in the following code, the first iteration gets a length of 1, but the second, looking up index 5, gives 1119887324. This is way too big for my data, which is only 3526 bytes (the whole frame is a single colour so likely to be small once encoded) :



```
while (index &lt; message->size()) {&#xA;assert(index &#x2B; 4 &lt; message->size());&#xA;auto lengthPtr = (uint32_t *)(message->data() &#x2B; index);&#xA;uint32_t length = ntohl(*lengthPtr);&#xA;auto naluStartIndex = index &#x2B; 4;&#xA;auto naluEndIndex = naluStartIndex &#x2B; length;&#xA;assert(naluEndIndex &lt;= message->size());    &#xA;        &#xA;auto begin = message->begin() &#x2B; naluStartIndex;&#xA;auto end = message->begin() &#x2B; naluEndIndex;&#xA;nalus->push_back(std::make_shared<nalunit>(begin, end));&#xA;index = naluEndIndex;&#xA;}&#xA;</nalunit>
```



Here is a dump of



```
uint32_t length = ntohl(*lengthPtr);&#xA;
```



for the first few elements of the message (*lengthPtr in parentheses) :



```
[2022-03-29 15:12:01.182] [info] index 0: 1  (16777216)&#xA;[2022-03-29 15:12:01.183] [info] index 1: 359  (1728118784)&#xA;[2022-03-29 15:12:01.184] [info] index 2: 91970  (1114046720)&#xA;[2022-03-29 15:12:01.186] [info] index 3: 23544512  (3225577217)&#xA;[2022-03-29 15:12:01.186] [info] index 4: 1732427807  (532693607)&#xA;[2022-03-29 15:12:01.187] [info] index 5: 1119887324  (3693068354)&#xA;[2022-03-29 15:12:01.188] [info] index 6: 3223313413  (98312128)&#xA;[2022-03-29 15:12:01.188] [info] index 7: 534512896  (384031)&#xA;[2022-03-29 15:12:01.188] [info] index 8: 3691315291  (1526728156)&#xA;[2022-03-29 15:12:01.189] [info] index 9: 83909537  (2707095557)&#xA;[2022-03-29 15:12:01.189] [info] index 10: 6004992  (10574592)&#xA;[2022-03-29 15:12:01.190] [info] index 11: 1537277952  (41307)&#xA;[2022-03-29 15:12:01.190] [info] index 12: 2701131779  (50331809)&#xA;[2022-03-29 15:12:01.192] [info] index 13: 768  (196608)&#xA;
```



(I know I should post a complete sample, I am working on it)



- I am fairly sure I am just missing something basic. E.g. am I supposed to do something with the AVPacket side_data, does AVPacket have or miss some header info ?
  
  
  
- If I just fwrite the pkt->data for a single frame to disk, I can read the codec information with ffprobe :
  
  
  


```
Input #0, h264, from &#x27;encodedOut.h264&#x27;:&#xA;Duration: N/A, bitrate: N/A&#xA;Stream #0:0: Video: h264 (Constrained Baseline), yuv420p(progressive), 1280x720, 30 tbr, 1200k tbn&#xA;
```



Update : This issue is solved by changing the H264RtpPacketizer separator setting from H264RtpPacketizer::Separator::Length to H264RtpPacketizer::Separator::LongStartSequence, many thanks to author of libdatachannel paullouisageneau (see answer below)




I have issues related to settings for the libx264 encoder, but can happily encode with h264_nvenc and h264_mf

Using and building FFMPEG library in Android Studio(Cmake)

8 septembre 2017, par y3k00000