avformat_open_input fails only with a custom IO context

Question

Running into an odd issue with avformat_open_input, it is failing with:

Invalid data found when processing input

But this only happens when I attempt to read the file using a custom AVIOContext.

My custom code is as follows (error checking omitted for clarity):

auto fmtCtx = avformat_alloc_context();
auto ioBufferSize = 32768;
auto ioBuffer = (unsigned char *)av_malloc(ioBufferSize);
auto ioCtx = avio_alloc_context(ioBuffer,
                                ioBufferSize,
                                0,
                                reinterpret_cast<void *>(this),
                                &imageIORead,
                                NULL,
                                &imageIOSeek));

fmtCtx -> pb = ioCtx;
fmtCtx -> flags |= AVFMT_FLAG_CUSTOM_IO;

int err = avformat_open_input(&fmtCtx, NULL, NULL, NULL);

imageIOSeek is never called, but properly handles the whence parameter including the AVSEEK_SIZE option. My file data is already loaded in memory, so imageIORead is trivial (returning 0 at EOF):

int imageIORead(void *opaque, uint8_t *buf, int buf_size) {
    Image *d = (Image *)buf;
    int rc = std::min(buf_size, static_cast<int>(d->data.size() - d->pos));

    memcpy(buf, d->data.data() + d->pos, rc);
    d->pos += rc;
    return rc;
}

The data being read is loaded from a file on disk:

/tmp/25.jpeg

The following code is able to open and extract the image correctly:

auto fmtCtx = avformat_alloc_context();
int err = avformat_open_input(&fmtCtx, "/tmp/25.jpeg", NULL, NULL);

The project is using a minified version of libavformat including only the formats we need. I don't believe this is the cause of the problem since the file can be open and handled properly when the path is specified. I haven't seen any configure options specifically targeting support for custom IO contexts.

This is the image in question: 25.jpeg

Answer 1

The problem was caused by a my compiling ffmpeg with a custom configure script trying to disable all the formats I have no use for.

If I remember correctly the missing configure flag was --enable-protocol=pipe.

This is the list of arguments to configure that I'm using to enable only audio and image file formats of interest to my application and thus create a cut down ffmpeg build:

--disable-doc
--disable-debug
--disable-avdevice
--enable-swscale
--enable-rdft
--disable-ffmpeg
--disable-ffplay
--disable-ffprobe
--disable-ffserver
--disable-network
--disable-muxers
--disable-demuxers
--disable-zlib
--disable-bzlib
--disable-iconv
--disable-bsfs
--disable-filters
--disable-parsers
--disable-indevs
--disable-outdevs
--disable-encoders
--disable-decoders
--disable-hwaccels
--disable-nvenc
--disable-xvmc
--disable-videotoolbox
--disable-audiotoolbox
--disable-libxcb
--disable-network
--disable-sdl2
--disable-securetransport
--disable-xlib
--disable-filters
--enable-filter=aformat
--enable-filter=anull
--enable-filter=atrim
--enable-filter=format
--enable-filter=null
--enable-filter=setpts
--enable-filter=trim
--disable-protocols
--enable-protocol=file
--enable-protocol=pipe
--enable-demuxer=image2
--enable-demuxer=aac
--enable-demuxer=ac3
--enable-demuxer=aiff
--enable-demuxer=ape
--enable-demuxer=asf
--enable-demuxer=au
--enable-demuxer=avi
--enable-demuxer=flac
--enable-demuxer=flv
--enable-demuxer=matroska
--enable-demuxer=mov
--enable-demuxer=m4v
--enable-demuxer=mp3
--enable-demuxer=mpc
--enable-demuxer=mpc8
--enable-demuxer=ogg
--enable-demuxer=pcm_alaw
--enable-demuxer=pcm_mulaw
--enable-demuxer=pcm_f64be
--enable-demuxer=pcm_f64le
--enable-demuxer=pcm_f32be
--enable-demuxer=pcm_f32le
--enable-demuxer=pcm_s32be
--enable-demuxer=pcm_s32le
--enable-demuxer=pcm_s24be
--enable-demuxer=pcm_s24le
--enable-demuxer=pcm_s16be
--enable-demuxer=pcm_s16le
--enable-demuxer=pcm_s8
--enable-demuxer=pcm_u32be
--enable-demuxer=pcm_u32le
--enable-demuxer=pcm_u24be
--enable-demuxer=pcm_u24le
--enable-demuxer=pcm_u16be
--enable-demuxer=pcm_u16le
--enable-demuxer=pcm_u8
--enable-demuxer=rm
--enable-demuxer=shorten
--enable-demuxer=tak
--enable-demuxer=tta
--enable-demuxer=wav
--enable-demuxer=wv
--enable-demuxer=xwma
--enable-demuxer=dsf
--enable-decoder=aac
--enable-decoder=aac_latm
--enable-decoder=ac3
--enable-decoder=alac
--enable-decoder=als
--enable-decoder=ape
--enable-decoder=atrac1
--enable-decoder=atrac3
--enable-decoder=eac3
--enable-decoder=flac
--enable-decoder=gsm
--enable-decoder=gsm_ms
--enable-decoder=mp1
--enable-decoder=mp1float
--enable-decoder=mp2
--enable-decoder=mp2float
--enable-decoder=mp3
--enable-decoder=mp3adu
--enable-decoder=mp3adufloat
--enable-decoder=mp3float
--enable-decoder=mp3on4
--enable-decoder=mp3on4float
--enable-decoder=mpc7
--enable-decoder=mpc8
--enable-decoder=opus
--enable-decoder=ra_144
--enable-decoder=ra_288
--enable-decoder=ralf
--enable-decoder=shorten
--enable-decoder=tak
--enable-decoder=tta
--enable-decoder=vorbis
--enable-decoder=wavpack
--enable-decoder=wmalossless
--enable-decoder=wmapro
--enable-decoder=wmav1
--enable-decoder=wmav2
--enable-decoder=wmavoice
--enable-decoder=pcm_alaw
--enable-decoder=pcm_bluray
--enable-decoder=pcm_dvd
--enable-decoder=pcm_f32be
--enable-decoder=pcm_f32le
--enable-decoder=pcm_f64be
--enable-decoder=pcm_f64le
--enable-decoder=pcm_lxf
--enable-decoder=pcm_mulaw
--enable-decoder=pcm_s8
--enable-decoder=pcm_s8_planar
--enable-decoder=pcm_s16be
--enable-decoder=pcm_s16be_planar
--enable-decoder=pcm_s16le
--enable-decoder=pcm_s16le_planar
--enable-decoder=pcm_s24be
--enable-decoder=pcm_s24daud
--enable-decoder=pcm_s24le
--enable-decoder=pcm_s24le_planar
--enable-decoder=pcm_s32be
--enable-decoder=pcm_s32le
--enable-decoder=pcm_s32le_planar
--enable-decoder=pcm_u8
--enable-decoder=pcm_u16be
--enable-decoder=pcm_u16le
--enable-decoder=pcm_u24be
--enable-decoder=pcm_u24le
--enable-decoder=pcm_u32be
--enable-decoder=pcm_u32le
--enable-decoder=pcm_zork
--enable-decoder=dsd_lsbf
--enable-decoder=dsd_msbf
--enable-decoder=dsd_lsbf_planar
--enable-decoder=dsd_msbf_planar
--enable-parser=aac
--enable-parser=aac_latm
--enable-parser=ac3
--enable-parser=cook
--enable-parser=dca
--enable-parser=flac
--enable-parser=gsm
--enable-parser=mpegaudio
--enable-parser=tak
--enable-parser=vorbis
--enable-decoder=bmp
--enable-decoder=gif
--enable-decoder=jpeg2000
--enable-decoder=jpegls
--enable-decoder=mjpeg
--enable-decoder=mjpegb
--enable-decoder=pgm
--enable-decoder=png
--enable-decoder=ppm
--enable-decoder=tiff
--enable-demuxer=gif
--enable-demuxer=image2pipe
--enable-demuxer=image_bmp_pipe
--enable-demuxer=image_jpeg_pipe
--enable-demuxer=image_jpegls_pipe
--enable-demuxer=image_pgm_pipe
--enable-demuxer=image_png_pipe
--enable-demuxer=image_tiff_pipe
--enable-demuxer=mjpeg
--enable-demuxer=mjpeg_2000
--enable-encoder=mjpeg
--enable-encoder=png
--enable-muxer=image2
--enable-muxer=mjpeg
--enable-muxer=singlejpeg
--enable-parser=bmp
--enable-parser=mjpeg
--enable-parser=png
--enable-parser=pnm
--enable-bsf=mjpeg2jpeg

It is quite possible that the list contains some extra features not strictly needed for audio and image processing, but these options solved the reported problem.